From e91539f7e2ee4f4f43cca9a1b0ebc2b1eaf73241 Mon Sep 17 00:00:00 2001
From: Benjamin DeMann <benjamin.demann@gmail.com>
Date: Wed, 3 Jul 2024 09:32:42 -0600
Subject: [PATCH] bonus return types

---
 benchmark/index.ts                            |  2 +-
 benchmark/markdown.ts                         |  4 +-
 benchmark/setup.ts                            |  2 +-
 dfx/index.ts                                  |  4 +-
 examples/apollo_server/src/index.ts           | 21 +++-
 .../src/backend/range_response.ts             |  2 +-
 examples/basic_bitcoin/test/bitcoin.ts        |  6 +-
 examples/bitcoin/test/setup.ts                |  2 +-
 .../scripts/bitcoin/transaction_count.js      |  1 +
 examples/ckbtc/test/pretest.ts                |  2 +-
 examples/ckbtc/wallet/backend/index.ts        |  2 +-
 .../ckbtc/wallet/frontend/elements/ck-app.ts  | 23 ++---
 .../composite_queries/src/canister1/index.ts  |  4 +-
 examples/ethereum_json_rpc/src/index.ts       |  7 +-
 examples/express/src/backend/index.ts         |  2 +-
 examples/express/src/frontend/index.ts        | 12 +--
 examples/fetch_ic/src/frontend/index.ts       | 36 +++----
 examples/guard_functions/src/guards.ts        | 14 +--
 examples/hello_world/src/frontend/index.ts    |  6 +-
 examples/imports/src/library.ts               |  6 +-
 .../internet_identity/src/frontend/index.ts   | 14 +--
 .../large_files/test/generate_test_files.ts   |  2 +-
 examples/large_files/test/tests.ts            |  2 +-
 examples/management_canister/src/index.ts     |  2 +-
 examples/management_canister/test/tests.ts    |  2 +-
 .../threshold_ecdsa/src/index.ts              |  4 +-
 examples/nest/src/app.controller.ts           |  2 +-
 examples/nest/src/cats/cats.controller.ts     |  2 +-
 examples/nest/src/dogs/dogs.controller.ts     |  2 +-
 examples/nest/src/main.ts                     |  2 +-
 .../robust_imports/src/azle_coverage/index.ts |  2 +-
 .../src/type_alias_decls/index.ts             |  2 +-
 examples/sqlite/src/entities/posts/router.ts  |  2 +-
 examples/sqlite/src/entities/users/router.ts  |  2 +-
 .../src/entities/users/router.ts              |  2 +-
 .../src/entities/posts/router.ts              |  2 +-
 .../src/entities/users/router.ts              |  2 +-
 examples/tfjs/src/api.ts                      |  2 +-
 examples/timers/src/timers.ts                 |  6 +-
 examples/vanilla_js/src/library.js            |  1 +
 http_client/fetch_ic/call.ts                  |  2 +-
 http_client/fetch_ic/index.ts                 |  4 +-
 .../constructed/tuple_arb/definition_arb.ts   |  4 +-
 .../constructed/tuple_arb/values_arbs.ts      |  4 +-
 .../candid/constructed/vec_arb/values_arb.ts  |  2 +-
 .../candid/primitive/ints/index.ts            |  2 +-
 .../candid/primitive/nats/index.ts            |  2 +-
 .../candid/reference/principal_arb.ts         |  2 +-
 .../reference/service_arb/definition_arb.ts   |  4 +-
 .../service_arb/service_method_arb.ts         |  2 +-
 .../candid/to_src_literal/string.ts           |  2 +-
 property_tests/arbitraries/canister_arb.ts    |  4 +-
 .../inspect_message_method_arb.ts             |  2 +-
 .../pre_upgrade_method_arb.ts                 |  2 +-
 .../canister_methods/query_method_arb.ts      |  2 +-
 .../canister_methods/update_method_arb.ts     |  2 +-
 property_tests/arbitraries/http/body_arb.ts   |  2 +-
 .../arbitraries/http/headers_arb.ts           |  2 +-
 .../arbitraries/http/response_arb.ts          |  2 +-
 .../arbitraries/unique_identifier_arb.ts      |  4 +-
 .../arbitraries/unique_primitive_arb.ts       |  6 +-
 .../are_params_correctly_ordered.ts           |  2 +-
 property_tests/get_actor.ts                   |  2 +-
 property_tests/index.ts                       |  2 +-
 property_tests/test/index.ts                  |  6 +-
 .../tests/blob/test/generate_tests.ts         |  4 +-
 .../tests/bool/test/generate_tests.ts         |  4 +-
 .../http_request/test/fletch.ts               |  6 +-
 .../http_request/test/generate_body.ts        | 15 +--
 .../http_request/test/generate_tests.ts       |  4 +-
 .../http_request_update/test/fletch.ts        |  6 +-
 .../http_request_update/test/generate_body.ts | 15 +--
 .../test/generate_tests.ts                    |  8 +-
 .../test/generate_callable_method_body.ts     |  2 +-
 .../init/test/generate_init_body.ts           |  2 +-
 .../init/test/generate_tests.ts               |  4 +-
 .../inspect_message/test/generate_tests.ts    |  4 +-
 .../test/generate_callable_method_body.ts     |  2 +-
 .../test/generate_init_method_body.ts         |  2 +-
 .../post_upgrade/test/generate_init_tests.ts  |  4 +-
 .../test/generate_post_upgrade_method_body.ts |  2 +-
 .../test/generate_post_upgrade_tests.ts       |  4 +-
 .../post_upgrade/test/global_var_name.ts      |  4 +-
 .../canister_methods/pre_upgrade/test/test.ts |  6 +-
 .../query/test/generate_tests.ts              |  4 +-
 .../update/test/generate_tests.ts             |  4 +-
 .../tests/float32/test/generate_tests.ts      |  4 +-
 .../tests/float64/test/generate_tests.ts      |  4 +-
 .../tests/func/test/generate_tests.ts         |  4 +-
 .../tests/int/test/generate_tests.ts          |  4 +-
 .../tests/int16/test/generate_tests.ts        |  4 +-
 .../tests/int32/test/generate_tests.ts        |  4 +-
 .../tests/int64/test/generate_tests.ts        |  4 +-
 .../tests/int8/test/generate_tests.ts         |  4 +-
 .../tests/nat/test/generate_tests.ts          |  4 +-
 .../tests/nat16/test/generate_tests.ts        |  4 +-
 .../tests/nat32/test/generate_tests.ts        |  4 +-
 .../tests/nat64/test/generate_tests.ts        |  4 +-
 .../tests/nat8/test/generate_tests.ts         |  4 +-
 .../tests/null/test/generate_tests.ts         |  4 +-
 .../tests/opt/test/generate_tests.ts          |  4 +-
 .../tests/principal/test/generate_tests.ts    |  4 +-
 .../tests/record/test/generate_tests.ts       |  4 +-
 .../tests/recursive/test/generate_tests.ts    |  4 +-
 .../tests/service/test/generate_tests.ts      |  4 +-
 .../stable_b_tree_map/test/contains_key.ts    | 12 ++-
 .../tests/stable_b_tree_map/test/get.ts       | 12 ++-
 .../tests/stable_b_tree_map/test/insert.ts    |  8 +-
 .../tests/stable_b_tree_map/test/is_empty.ts  | 12 ++-
 .../tests/stable_b_tree_map/test/items.ts     | 12 ++-
 .../tests/stable_b_tree_map/test/keys.ts      | 12 ++-
 .../tests/stable_b_tree_map/test/len.ts       | 12 ++-
 .../tests/stable_b_tree_map/test/remove.ts    |  8 +-
 .../tests/stable_b_tree_map/test/values.ts    | 12 ++-
 .../tests/text/test/generate_tests.ts         |  4 +-
 .../tests/tuple/test/generate_tests.ts        |  4 +-
 .../tests/variant/test/generate_tests.ts      |  4 +-
 .../tests/vec/test/generate_tests.ts          |  4 +-
 property_tests/visitors/cli-string-visitor.ts |  4 +-
 scripts/add_metadata_to_dfx_json.js           |  1 +
 scripts/class_migration/clean_package.js      |  1 +
 .../copy_generated_candid_from_example.js     |  1 +
 scripts/class_migration/delete_tests_file.js  |  1 +
 scripts/file_generator/index.ts               | 14 ++-
 scripts/file_generator/main.ts                |  4 +-
 scripts/hash_file/main.ts                     |  2 +-
 scripts/reorder_dfx_json.js                   |  1 +
 scripts/simplify_tsconfig.js                  |  1 +
 scripts/update_dfx_json_main.js               |  1 +
 src/compiler/compile_rust_code.ts             |  6 +-
 ...rust_code_with_candid_and_compiler_info.ts |  2 +-
 src/compiler/custom_js_modules/perf_hooks.ts  |  2 +-
 src/compiler/file_uploader/expand_paths.ts    |  4 +-
 src/compiler/file_uploader/index.ts           |  5 +-
 src/compiler/file_uploader/on_before_exit.ts  |  7 +-
 src/compiler/file_uploader/ongoing_hashes.ts  |  4 +-
 src/compiler/file_uploader/upload_file.ts     |  4 +-
 src/compiler/file_watcher/file_watcher.ts     |  2 +-
 .../file_watcher/setup_file_watcher.ts        |  2 +-
 .../generate_candid_and_canister_methods.ts   | 96 +++++++++----------
 src/compiler/get_consumer_config.ts           |  2 +-
 src/compiler/handle_cli.ts                    | 10 +-
 src/compiler/index.ts                         |  8 +-
 src/compiler/new_command.ts                   |  2 +-
 src/compiler/prepare_docker_image.ts          | 12 +--
 src/compiler/prepare_rust_staging_area.ts     |  2 +-
 src/compiler/utils/global_paths.ts            |  2 +-
 .../candid/did_file/visitor/visit/service.ts  |  2 +-
 .../visitors/visit/variant/azle_result.ts     |  3 +-
 .../visitors/visit/variant/azle_variant.ts    |  3 +-
 src/lib/candid/types/constructed/blob.ts      |  8 +-
 src/lib/candid/types/constructed/opt.ts       |  8 +-
 src/lib/candid/types/constructed/record.ts    |  4 +-
 src/lib/candid/types/constructed/tuple.ts     |  6 +-
 src/lib/candid/types/constructed/variant.ts   |  4 +-
 src/lib/candid/types/constructed/vec.ts       |  8 +-
 src/lib/candid/types/primitive/bool.ts        |  8 +-
 src/lib/candid/types/primitive/empty.ts       |  8 +-
 .../candid/types/primitive/floats/float32.ts  |  8 +-
 .../candid/types/primitive/floats/float64.ts  |  8 +-
 src/lib/candid/types/primitive/ints/int.ts    |  8 +-
 src/lib/candid/types/primitive/ints/int16.ts  |  8 +-
 src/lib/candid/types/primitive/ints/int32.ts  |  8 +-
 src/lib/candid/types/primitive/ints/int64.ts  |  8 +-
 src/lib/candid/types/primitive/ints/int8.ts   |  8 +-
 src/lib/candid/types/primitive/nats/nat.ts    |  8 +-
 src/lib/candid/types/primitive/nats/nat16.ts  |  8 +-
 src/lib/candid/types/primitive/nats/nat32.ts  |  8 +-
 src/lib/candid/types/primitive/nats/nat64.ts  |  8 +-
 src/lib/candid/types/primitive/nats/nat8.ts   |  8 +-
 src/lib/candid/types/primitive/null.ts        |  8 +-
 src/lib/candid/types/primitive/reserved.ts    |  6 +-
 src/lib/candid/types/primitive/text.ts        |  8 +-
 src/lib/candid/types/primitive/void.ts        |  6 +-
 src/lib/candid/types/reference/func.ts        |  8 +-
 src/lib/candid/types/reference/principal.ts   |  8 +-
 .../service/canister_function/index.ts        |  2 +-
 .../service/canister_function/query_update.ts |  2 +-
 src/lib/canister_methods/execute_method.ts    |  4 +-
 src/lib/canister_methods/is_async.ts          |  2 +-
 src/lib/canister_methods/methods/heartbeat.ts |  2 +-
 src/lib/canister_methods/methods/init.ts      |  2 +-
 .../methods/inspect_message.ts                |  2 +-
 .../canister_methods/methods/post_upgrade.ts  |  2 +-
 src/lib/canister_methods/methods/query.ts     |  2 +-
 src/lib/canister_methods/methods/update.ts    |  2 +-
 src/lib/fetch/headers.ts                      | 20 ++--
 src/lib/fetch/index.ts                        |  4 +-
 src/lib/globals.ts                            | 10 +-
 src/lib/ic/call_raw.ts                        |  6 +-
 src/lib/ic/call_raw_128.ts                    |  6 +-
 src/lib/ic/set_outgoing_http_options.ts       |  2 +-
 src/lib/ic/set_timer.ts                       |  2 +-
 src/lib/stable/error.ts                       |  6 +-
 src/lib/stable/execute_with_candid_serde.ts   |  2 +-
 src/lib/stable/guard.ts                       |  2 +-
 src/lib/stable/ic_apis/call.ts                |  6 +-
 .../ic_apis/set_outgoing_http_options.ts      |  2 +-
 src/lib/stable/ic_apis/set_timer.ts           |  2 +-
 src/lib/stable/init.ts                        |  2 +-
 src/lib/stable/mark_experimental.ts           |  2 +-
 src/lib/stable/post_upgrade.ts                |  2 +-
 src/lib/stable/query.ts                       |  2 +-
 src/lib/stable/update.ts                      |  2 +-
 src/lib/stable_structures/stable_json.ts      |  4 +-
 src/lib/system_types/result.ts                | 12 +--
 206 files changed, 591 insertions(+), 515 deletions(-)

diff --git a/benchmark/index.ts b/benchmark/index.ts
index 44de6f4a66..a18575d54b 100644
--- a/benchmark/index.ts
+++ b/benchmark/index.ts
@@ -516,7 +516,7 @@ function write_reports_to_file(
     output_file: string,
     benchmark_results: BenchmarkResult[],
     num_benchmark_iterations: number
-) {
+): void {
     const markdown_report = create_markdown_report(
         benchmark_results,
         num_benchmark_iterations,
diff --git a/benchmark/markdown.ts b/benchmark/markdown.ts
index d505cd7235..f38c3ff262 100644
--- a/benchmark/markdown.ts
+++ b/benchmark/markdown.ts
@@ -1655,7 +1655,7 @@ function generate_benchmarks_string(
     )}`;
 }
 
-function format_number_to_rust(number: string | number | bigint) {
+function format_number_to_rust(number: string | number | bigint): string {
     const number_is_negative = number.toString()[0] === '-';
     const number_is_decimal_less_than_one =
         (number_is_negative === false && Number(number) < 1) ||
@@ -1683,7 +1683,7 @@ function format_number_to_rust(number: string | number | bigint) {
     );
 }
 
-function format_number_to_usd(number: number) {
+function format_number_to_usd(number: number): string {
     return number.toLocaleString('en-US', {
         style: 'currency',
         currency: 'USD',
diff --git a/benchmark/setup.ts b/benchmark/setup.ts
index f3870cd0a2..d6a494957e 100644
--- a/benchmark/setup.ts
+++ b/benchmark/setup.ts
@@ -1,6 +1,6 @@
 import { execSync } from 'child_process';
 
-export async function run_setup(argument?: string) {
+export async function run_setup(argument?: string): Promise<void> {
     execSync(`dfx canister create azle`, {
         stdio: 'inherit'
     });
diff --git a/dfx/index.ts b/dfx/index.ts
index 180b1584a0..a2bb0814f2 100644
--- a/dfx/index.ts
+++ b/dfx/index.ts
@@ -28,7 +28,7 @@ export function getAgentHost(): string {
         : `http://127.0.0.1:${getWebServerPort()}`;
 }
 
-export async function createAnonymousAgent() {
+export async function createAnonymousAgent(): Promise<void> {
     const agent = new HttpAgent({
         host: getAgentHost()
     });
@@ -185,7 +185,7 @@ export function addController(
     canisterName: string,
     identityName: string,
     principal: string
-) {
+): Buffer {
     const currentIdentity = whoami();
     console.info();
     console.info(`Adding ${identityName} as a controller for ${canisterName}`);
diff --git a/examples/apollo_server/src/index.ts b/examples/apollo_server/src/index.ts
index 31629d5415..e39cc0c945 100644
--- a/examples/apollo_server/src/index.ts
+++ b/examples/apollo_server/src/index.ts
@@ -34,6 +34,17 @@ const typeDefs = `#graphql
   }
 `;
 
+type Book = {
+    id: string;
+    title: string;
+    rating: number;
+};
+
+type Author = {
+    id: string;
+    name: string;
+};
+
 let books = [
     {
         id: '0',
@@ -62,14 +73,14 @@ const authors = [
 // This resolver retrieves books from the "books" array above.
 const resolvers = {
     Query: {
-        books: () => books,
-        authors: () => authors,
-        titles: () => {
+        books: (): Book[] => books,
+        authors: (): Author[] => authors,
+        titles: (): string[] => {
             return books.map((book) => book.title);
         }
     },
     Mutation: {
-        createBook: (parent: any, args: any) => {
+        createBook: (parent: any, args: any): Book => {
             const book = {
                 id: books.length.toString(),
                 title: args.title,
@@ -83,7 +94,7 @@ const resolvers = {
     }
 };
 
-async function init() {
+async function init(): Promise<void> {
     const app = express();
 
     const server = new ApolloServer({
diff --git a/examples/audio_and_video/src/backend/range_response.ts b/examples/audio_and_video/src/backend/range_response.ts
index e27fdeeb81..df81a96e6f 100644
--- a/examples/audio_and_video/src/backend/range_response.ts
+++ b/examples/audio_and_video/src/backend/range_response.ts
@@ -3,7 +3,7 @@ import { createReadStream, statSync } from 'fs';
 import parseRange from 'range-parser';
 
 export function rangeResponse(maxRange: number = 3_000_000) {
-    return async (req: Request, res: Response) => {
+    return async (req: Request, res: Response): Promise<void> => {
         const filePath = req.originalUrl;
         const fileLength = statSync(filePath).size;
 
diff --git a/examples/basic_bitcoin/test/bitcoin.ts b/examples/basic_bitcoin/test/bitcoin.ts
index bf7d119c11..12c492881d 100644
--- a/examples/basic_bitcoin/test/bitcoin.ts
+++ b/examples/basic_bitcoin/test/bitcoin.ts
@@ -1,19 +1,19 @@
 import { Transaction } from 'bitcoinjs-lib';
 import { execSync } from 'child_process';
 
-export function generateToAddress(address: string, blocks: number) {
+export function generateToAddress(address: string, blocks: number): void {
     execSync(
         `.bitcoin/bin/bitcoin-cli -conf=$(pwd)/.bitcoin.conf generatetoaddress ${blocks} ${address}`
     );
 }
 
-export function generate(blocks: number) {
+export function generate(blocks: number): void {
     execSync(
         `.bitcoin/bin/bitcoin-cli -conf=$(pwd)/.bitcoin.conf -generate ${blocks}`
     );
 }
 
-export function createWallet(name: string) {
+export function createWallet(name: string): void {
     execSync(
         `.bitcoin/bin/bitcoin-cli -conf=$(pwd)/.bitcoin.conf createwallet ${name}`
     );
diff --git a/examples/bitcoin/test/setup.ts b/examples/bitcoin/test/setup.ts
index 3652aa25ca..28661b4756 100644
--- a/examples/bitcoin/test/setup.ts
+++ b/examples/bitcoin/test/setup.ts
@@ -68,7 +68,7 @@ export function createTransaction(from: Utxo, wallets: Wallets): string {
     return bitcoinCli.createRawTransaction(input, outputs);
 }
 
-export function signTransaction(rawTransaction: string) {
+export function signTransaction(rawTransaction: string): string {
     console.log(' - sign transaction');
     return bitcoinCli.signRawTransactionWithWallet(rawTransaction).hex;
 }
diff --git a/examples/bitcoin_psbt/scripts/bitcoin/transaction_count.js b/examples/bitcoin_psbt/scripts/bitcoin/transaction_count.js
index 1785372ed5..63c8774d2b 100644
--- a/examples/bitcoin_psbt/scripts/bitcoin/transaction_count.js
+++ b/examples/bitcoin_psbt/scripts/bitcoin/transaction_count.js
@@ -1,3 +1,4 @@
+/* eslint-disable @typescript-eslint/explicit-function-return-type */
 // eslint-disable-next-line @typescript-eslint/no-var-requires
 const { execSync } = require('child_process');
 
diff --git a/examples/ckbtc/test/pretest.ts b/examples/ckbtc/test/pretest.ts
index 29f6d9ce2a..5b1d9c5537 100644
--- a/examples/ckbtc/test/pretest.ts
+++ b/examples/ckbtc/test/pretest.ts
@@ -15,7 +15,7 @@ function pretest(): void {
     });
 }
 
-function uninstall(...canisterNames: string[]) {
+function uninstall(...canisterNames: string[]): void {
     canisterNames.forEach((canisterName) => {
         execSync(`dfx canister uninstall-code ${canisterName} || true`, {
             stdio: 'inherit'
diff --git a/examples/ckbtc/wallet/backend/index.ts b/examples/ckbtc/wallet/backend/index.ts
index 15af27900e..a3c8415457 100644
--- a/examples/ckbtc/wallet/backend/index.ts
+++ b/examples/ckbtc/wallet/backend/index.ts
@@ -211,7 +211,7 @@ function padPrincipalWithZeros(blob: blob): blob {
     return newUin8Array;
 }
 
-function setupCanisters() {
+function setupCanisters(): void {
     ckBTC = ICRC(
         Principal.fromText(
             process.env.CK_BTC_PRINCIPAL ??
diff --git a/examples/ckbtc/wallet/frontend/elements/ck-app.ts b/examples/ckbtc/wallet/frontend/elements/ck-app.ts
index b5118890ef..6526902d42 100644
--- a/examples/ckbtc/wallet/frontend/elements/ck-app.ts
+++ b/examples/ckbtc/wallet/frontend/elements/ck-app.ts
@@ -35,13 +35,13 @@ export class CkApp extends LitElement {
     @state()
     transferring: boolean = false;
 
-    async connectedCallback() {
+    async connectedCallback(): Promise<void> {
         super.connectedCallback();
 
         await this.authenticate();
     }
 
-    async authenticate() {
+    async authenticate(): Promise<void> {
         const authClient = await AuthClient.create();
 
         if (await authClient.isAuthenticated()) {
@@ -62,14 +62,14 @@ export class CkApp extends LitElement {
         }
     }
 
-    initialize() {
+    initialize(): void {
         this.createWalletBackend();
 
         this.getBalance();
         this.getBitcoinDepositAddress();
     }
 
-    createWalletBackend() {
+    createWalletBackend(): void {
         const agent = new HttpAgent({
             identity: this.identity
         });
@@ -89,7 +89,7 @@ export class CkApp extends LitElement {
         this.walletBackend = walletBackend;
     }
 
-    async getBalance() {
+    async getBalance(): Promise<void> {
         if (this.walletBackend === undefined) {
             alert(`walletBackend has not been initialized`);
             return;
@@ -102,7 +102,7 @@ export class CkApp extends LitElement {
         this.balance = result;
     }
 
-    async getBitcoinDepositAddress() {
+    async getBitcoinDepositAddress(): Promise<void> {
         if (this.walletBackend === undefined) {
             alert(`walletBackend has not been initialized`);
             return;
@@ -115,7 +115,7 @@ export class CkApp extends LitElement {
         this.bitcoinDepositAddress = result;
     }
 
-    async updateBalance() {
+    async updateBalance(): Promise<void> {
         this.updatingBalance = true;
 
         if (this.walletBackend === undefined) {
@@ -132,7 +132,7 @@ export class CkApp extends LitElement {
         this.updatingBalance = false;
     }
 
-    async transfer() {
+    async transfer(): Promise<void> {
         this.transferring = true;
 
         if (this.walletBackend === undefined) {
@@ -157,7 +157,7 @@ export class CkApp extends LitElement {
         this.transferring = false;
     }
 
-    render() {
+    render(): void {
         const identityPrincipalString = this.identity
             ? this.identity.getPrincipal().toText()
             : 'Loading...';
@@ -190,14 +190,15 @@ export class CkApp extends LitElement {
                     .disabled=${this.transferring}
                     type="text"
                     .value=${this.transferTo}
-                    @input=${(e: any) => (this.transferTo = e.target.value)}
+                    @input=${(e: any): void =>
+                        (this.transferTo = e.target.value)}
                 />
                 Amount:
                 <input
                     .disabled=${this.transferring}
                     type="number"
                     .value=${this.transferAmount}
-                    @input=${(e: any) =>
+                    @input=${(e: any): void =>
                         (this.transferAmount = BigInt(e.target.value))}
                 />
                 <button
diff --git a/examples/composite_queries/src/canister1/index.ts b/examples/composite_queries/src/canister1/index.ts
index ca8a2fd6c7..05ff405951 100644
--- a/examples/composite_queries/src/canister1/index.ts
+++ b/examples/composite_queries/src/canister1/index.ts
@@ -195,7 +195,7 @@ function getCanister2Principal(): string {
     throw new Error(`process.env.CANISTER2_PRINCIPAL is not defined`);
 }
 
-async function incCanister(canister: any, candidPath: string) {
+async function incCanister(canister: any, candidPath: string): Promise<any> {
     if (process.env.AZLE_TEST_FETCH === 'true') {
         const response = await fetch(
             `icp://${canister.principal.toText()}/incCounter`,
@@ -209,7 +209,7 @@ async function incCanister(canister: any, candidPath: string) {
     }
 }
 
-async function incCanister2() {
+async function incCanister2(): Promise<any> {
     if (process.env.AZLE_TEST_FETCH === 'true') {
         const response = await fetch(
             `icp://${getCanister2Principal()}/incCounter`,
diff --git a/examples/ethereum_json_rpc/src/index.ts b/examples/ethereum_json_rpc/src/index.ts
index f96ae75286..0411ffa3c6 100644
--- a/examples/ethereum_json_rpc/src/index.ts
+++ b/examples/ethereum_json_rpc/src/index.ts
@@ -52,7 +52,10 @@ export default Canister({
     })
 });
 
-async function getBalance(url: string, ethereumAddress: string) {
+async function getBalance(
+    url: string,
+    ethereumAddress: string
+): Promise<string> {
     if (process.env.AZLE_TEST_FETCH === 'true') {
         ic.setOutgoingHttpOptions({
             maxResponseBytes: 2_000n,
@@ -108,7 +111,7 @@ async function getBalance(url: string, ethereumAddress: string) {
         return Buffer.from(httpResponse.body.buffer).toString('utf-8');
     }
 }
-async function getBlockByNumber(url: string, number: number) {
+async function getBlockByNumber(url: string, number: number): Promise<string> {
     if (process.env.AZLE_TEST_FETCH === 'true') {
         ic.setOutgoingHttpOptions({
             maxResponseBytes: 2_000n,
diff --git a/examples/express/src/backend/index.ts b/examples/express/src/backend/index.ts
index b0d4556719..47789a5cd8 100644
--- a/examples/express/src/backend/index.ts
+++ b/examples/express/src/backend/index.ts
@@ -69,7 +69,7 @@ app.use(express.static('/dist'));
 
 app.listen();
 
-function changeGlobalState(req: Request, res: Response) {
+function changeGlobalState(req: Request, res: Response): void {
     globalState = req.body;
 
     res.json(globalState);
diff --git a/examples/express/src/frontend/index.ts b/examples/express/src/frontend/index.ts
index 6edac62e9e..f8b96a0e93 100644
--- a/examples/express/src/frontend/index.ts
+++ b/examples/express/src/frontend/index.ts
@@ -19,7 +19,7 @@ export class AzleApp extends LitElement {
     @property()
     globalStateResponse: string = JSON.stringify({});
 
-    async testResSend() {
+    async testResSend(): Promise<void> {
         this.resSendResponse = 'Loading...';
 
         const response = await fetch(`${this.canisterOrigin}/res-send`);
@@ -28,7 +28,7 @@ export class AzleApp extends LitElement {
         this.resSendResponse = responseText;
     }
 
-    async testResWrite() {
+    async testResWrite(): Promise<void> {
         this.resWriteResponse = 'Loading...';
 
         const response = await fetch(`${this.canisterOrigin}/res-write`);
@@ -37,7 +37,7 @@ export class AzleApp extends LitElement {
         this.resWriteResponse = responseText;
     }
 
-    async testFileStream() {
+    async testFileStream(): Promise<void> {
         this.fileStreamResponse = 'Loading...';
 
         const response = await fetch(`${this.canisterOrigin}/file-stream`);
@@ -46,7 +46,7 @@ export class AzleApp extends LitElement {
         this.fileStreamResponse = responseText;
     }
 
-    async testGlobalState() {
+    async testGlobalState(): Promise<void> {
         this.globalStateResponse = 'Loading...';
 
         const response = await fetch(
@@ -64,7 +64,7 @@ export class AzleApp extends LitElement {
         this.globalStateResponse = JSON.stringify(responseJson);
     }
 
-    async deleteGlobalState() {
+    async deleteGlobalState(): Promise<void> {
         this.globalStateResponse = 'Loading...';
 
         const response = await fetch(
@@ -78,7 +78,7 @@ export class AzleApp extends LitElement {
         this.globalStateResponse = JSON.stringify(responseJson);
     }
 
-    render() {
+    render(): any {
         return html`
             <h1>Azle Express App</h1>
 
diff --git a/examples/fetch_ic/src/frontend/index.ts b/examples/fetch_ic/src/frontend/index.ts
index 1ee632ac45..f0cd262fec 100644
--- a/examples/fetch_ic/src/frontend/index.ts
+++ b/examples/fetch_ic/src/frontend/index.ts
@@ -9,12 +9,12 @@ export class AzleApp extends LitElement {
     @property()
     identity: Identity | null = null;
 
-    connectedCallback() {
+    connectedCallback(): void {
         super.connectedCallback();
         this.authenticate();
     }
 
-    async authenticate() {
+    async authenticate(): Promise<void> {
         const authClient = await AuthClient.create();
         const isAuthenticated = await authClient.isAuthenticated();
 
@@ -25,11 +25,11 @@ export class AzleApp extends LitElement {
         }
     }
 
-    handleIsAuthenticated(authClient: AuthClient) {
+    handleIsAuthenticated(authClient: AuthClient): void {
         this.identity = authClient.getIdentity();
     }
 
-    async handleIsNotAuthenticated(authClient: AuthClient) {
+    async handleIsNotAuthenticated(authClient: AuthClient): Promise<void> {
         await new Promise((resolve, reject) => {
             authClient.login({
                 identityProvider: import.meta.env.VITE_IDENTITY_PROVIDER,
@@ -42,7 +42,7 @@ export class AzleApp extends LitElement {
         this.identity = authClient.getIdentity();
     }
 
-    async headersArray() {
+    async headersArray(): Promise<void> {
         if (this.identity === null) {
             throw new Error(`Identity must be defined`);
         }
@@ -80,7 +80,7 @@ export class AzleApp extends LitElement {
         }
     }
 
-    async headersObject() {
+    async headersObject(): Promise<void> {
         if (this.identity === null) {
             throw new Error(`Identity must be defined`);
         }
@@ -118,7 +118,7 @@ export class AzleApp extends LitElement {
         }
     }
 
-    async bodyUint8Array() {
+    async bodyUint8Array(): Promise<void> {
         if (this.identity === null) {
             throw new Error(`Identity must be defined`);
         }
@@ -160,7 +160,7 @@ export class AzleApp extends LitElement {
         }
     }
 
-    async bodyString() {
+    async bodyString(): Promise<void> {
         if (this.identity === null) {
             throw new Error(`Identity must be defined`);
         }
@@ -197,7 +197,7 @@ export class AzleApp extends LitElement {
         }
     }
 
-    async bodyArrayBuffer() {
+    async bodyArrayBuffer(): Promise<void> {
         if (this.identity === null) {
             throw new Error(`Identity must be defined`);
         }
@@ -239,7 +239,7 @@ export class AzleApp extends LitElement {
         }
     }
 
-    async bodyBlob() {
+    async bodyBlob(): Promise<void> {
         if (this.identity === null) {
             throw new Error(`Identity must be defined`);
         }
@@ -283,7 +283,7 @@ export class AzleApp extends LitElement {
         }
     }
 
-    async bodyDataView() {
+    async bodyDataView(): Promise<void> {
         if (this.identity === null) {
             throw new Error(`Identity must be defined`);
         }
@@ -327,7 +327,7 @@ export class AzleApp extends LitElement {
         }
     }
 
-    async urlQueryParamsGet() {
+    async urlQueryParamsGet(): Promise<void> {
         if (this.identity === null) {
             throw new Error(`Identity must be defined`);
         }
@@ -356,7 +356,7 @@ export class AzleApp extends LitElement {
         }
     }
 
-    async urlQueryParamsPost() {
+    async urlQueryParamsPost(): Promise<void> {
         if (this.identity === null) {
             throw new Error(`Identity must be defined`);
         }
@@ -386,7 +386,7 @@ export class AzleApp extends LitElement {
         }
     }
 
-    async notAuthorizedGet() {
+    async notAuthorizedGet(): Promise<void> {
         const response = await fetch(
             `${import.meta.env.VITE_CANISTER_ORIGIN}/not-authorized-get`,
             {
@@ -399,7 +399,7 @@ export class AzleApp extends LitElement {
         }
     }
 
-    async notAuthorizedPost() {
+    async notAuthorizedPost(): Promise<void> {
         const response = await fetch(
             `${import.meta.env.VITE_CANISTER_ORIGIN}/not-authorized-post`,
             {
@@ -413,7 +413,7 @@ export class AzleApp extends LitElement {
         }
     }
 
-    async head() {
+    async head(): Promise<void> {
         const response = await fetch(
             `${import.meta.env.VITE_CANISTER_ORIGIN}/head`,
             {
@@ -434,7 +434,7 @@ export class AzleApp extends LitElement {
         }
     }
 
-    async options() {
+    async options(): Promise<void> {
         const response = await fetch(
             `${import.meta.env.VITE_CANISTER_ORIGIN}/options`,
             {
@@ -451,7 +451,7 @@ export class AzleApp extends LitElement {
         }
     }
 
-    render() {
+    render(): any {
         return html`
             <h1>Test fetchIc</h1>
 
diff --git a/examples/guard_functions/src/guards.ts b/examples/guard_functions/src/guards.ts
index 5e2dce764c..416f5a0ed6 100644
--- a/examples/guard_functions/src/guards.ts
+++ b/examples/guard_functions/src/guards.ts
@@ -1,10 +1,10 @@
 import { state } from './index';
 
-export function allowAll() {
+export function allowAll(): void {
     console.log('allowAll called');
 }
 
-export function acceptAllThenRejectAll() {
+export function acceptAllThenRejectAll(): void {
     console.log('acceptAllThenRejectAll called');
     if (++state.heartbeatTick > 20) {
         console.log(`Heartbeat suppressed`);
@@ -13,17 +13,17 @@ export function acceptAllThenRejectAll() {
     console.log(`Accepted heartbeat tick #${state.heartbeatTick}`);
 }
 
-export function incrementCounterAndAllowAll() {
+export function incrementCounterAndAllowAll(): void {
     console.log('incrementCounterAndAllowAll called');
     state.counter++;
 }
 
-export function unpassable() {
+export function unpassable(): void {
     console.log('unpassable called');
     throw 'Execution halted by "unpassable" guard function';
 }
 
-export function throwString() {
+export function throwString(): void {
     console.log('throw string called');
     throw 'Execution halted by "throw string" guard function';
 }
@@ -35,14 +35,14 @@ class CustomError extends Error {
     }
 }
 
-export function throwCustomError() {
+export function throwCustomError(): void {
     console.log('throwCustomError called');
     throw new CustomError(
         'Execution halted by "throw custom error" guard function'
     );
 }
 
-export function returnNonStringErrValue() {
+export function returnNonStringErrValue(): void {
     console.log('nonStringErrValue called');
     throw { badProp: 'Something other than a string' };
 }
diff --git a/examples/hello_world/src/frontend/index.ts b/examples/hello_world/src/frontend/index.ts
index 2d2a79f98c..4b4a030d90 100644
--- a/examples/hello_world/src/frontend/index.ts
+++ b/examples/hello_world/src/frontend/index.ts
@@ -11,7 +11,7 @@ export class AzleApp extends LitElement {
         this.getDb();
     }
 
-    async getDb() {
+    async getDb(): Promise<void> {
         this.db = 'Loading...';
 
         const response = await fetch(
@@ -22,7 +22,7 @@ export class AzleApp extends LitElement {
         this.db = responseJson;
     }
 
-    async updateDb() {
+    async updateDb(): Promise<void> {
         this.db = 'Loading...';
 
         const response = await fetch(
@@ -40,7 +40,7 @@ export class AzleApp extends LitElement {
         this.db = responseJson;
     }
 
-    render() {
+    render(): any {
         return html`
             <h1>Azle Hello World</h1>
 
diff --git a/examples/imports/src/library.ts b/examples/imports/src/library.ts
index 67d6ef3432..0657f73e58 100644
--- a/examples/imports/src/library.ts
+++ b/examples/imports/src/library.ts
@@ -1,11 +1,11 @@
-export function one() {
+export function one(): string {
     return 'one';
 }
 
-export function two() {
+export function two(): string {
     return 'two';
 }
 
-export function three() {
+export function three(): string {
     return 'three';
 }
diff --git a/examples/internet_identity/src/frontend/index.ts b/examples/internet_identity/src/frontend/index.ts
index beeb22f1a3..e7f3727592 100644
--- a/examples/internet_identity/src/frontend/index.ts
+++ b/examples/internet_identity/src/frontend/index.ts
@@ -12,12 +12,12 @@ export class AzleApp extends LitElement {
     @property()
     whoami: string = '';
 
-    connectedCallback() {
+    connectedCallback(): void {
         super.connectedCallback();
         this.authenticate();
     }
 
-    async authenticate() {
+    async authenticate(): Promise<void> {
         const authClient = await AuthClient.create();
         const isAuthenticated = await authClient.isAuthenticated();
 
@@ -28,11 +28,11 @@ export class AzleApp extends LitElement {
         }
     }
 
-    handleIsAuthenticated(authClient: AuthClient) {
+    handleIsAuthenticated(authClient: AuthClient): void {
         this.identity = authClient.getIdentity();
     }
 
-    async handleIsNotAuthenticated(authClient: AuthClient) {
+    async handleIsNotAuthenticated(authClient: AuthClient): Promise<void> {
         await new Promise((resolve, reject) => {
             authClient.login({
                 identityProvider: import.meta.env.VITE_IDENTITY_PROVIDER,
@@ -45,7 +45,7 @@ export class AzleApp extends LitElement {
         this.identity = authClient.getIdentity();
     }
 
-    async whoamiUnauthenticated() {
+    async whoamiUnauthenticated(): Promise<void> {
         const response = await fetch(
             `${import.meta.env.VITE_CANISTER_ORIGIN}/whoami`
         );
@@ -54,7 +54,7 @@ export class AzleApp extends LitElement {
         this.whoami = responseText;
     }
 
-    async whoamiAuthenticated() {
+    async whoamiAuthenticated(): Promise<void> {
         const response = await fetch(
             `${import.meta.env.VITE_CANISTER_ORIGIN}/whoami`,
             {
@@ -67,7 +67,7 @@ export class AzleApp extends LitElement {
         this.whoami = responseText;
     }
 
-    render() {
+    render(): any {
         return html`
             <h1>Internet Identity</h1>
 
diff --git a/examples/large_files/test/generate_test_files.ts b/examples/large_files/test/generate_test_files.ts
index 14ed6fffc0..94e747d7b8 100644
--- a/examples/large_files/test/generate_test_files.ts
+++ b/examples/large_files/test/generate_test_files.ts
@@ -5,7 +5,7 @@ export async function generateTestFileOfSize(
     size: number,
     unit: Unit,
     dir: string = 'auto'
-) {
+): Promise<void> {
     const autoDir = join('assets', dir);
     const path = join(autoDir, `test${size}${unit}`);
     const fileSize = toBytes(size, unit);
diff --git a/examples/large_files/test/tests.ts b/examples/large_files/test/tests.ts
index 433ed80bc7..4719bd4a94 100644
--- a/examples/large_files/test/tests.ts
+++ b/examples/large_files/test/tests.ts
@@ -103,7 +103,7 @@ export function verifyUpload(
     origin: string,
     srcPath: string,
     destPath: string
-) {
+): void {
     it(`uploads and hashes ${srcPath}`, async () => {
         const localPath = join('assets', srcPath);
         const canisterPath = join('assets', destPath);
diff --git a/examples/management_canister/src/index.ts b/examples/management_canister/src/index.ts
index 4f3b0d5dcf..2ba98da279 100644
--- a/examples/management_canister/src/index.ts
+++ b/examples/management_canister/src/index.ts
@@ -469,7 +469,7 @@ export default Canister({
     })
 });
 
-async function createCanister() {
+async function createCanister(): Promise<any> {
     if (process.env.AZLE_TEST_FETCH === 'true') {
         const response = await fetch(`icp://aaaaa-aa/create_canister`, {
             body: serialize({
diff --git a/examples/management_canister/test/tests.ts b/examples/management_canister/test/tests.ts
index bc3278c51c..d779482ed8 100644
--- a/examples/management_canister/test/tests.ts
+++ b/examples/management_canister/test/tests.ts
@@ -7,7 +7,7 @@ import { readFileSync } from 'fs';
 import { _SERVICE } from './dfx_generated/management_canister/management_canister.did';
 
 export function getTests(managementCanister: ActorSubclass<_SERVICE>) {
-    return () => {
+    return (): void => {
         it('executes create_canister from the management canister', async () => {
             const result = await managementCanister.executeCreateCanister();
 
diff --git a/examples/motoko_examples/threshold_ecdsa/src/index.ts b/examples/motoko_examples/threshold_ecdsa/src/index.ts
index de9c7ce379..d2e1fa52fe 100644
--- a/examples/motoko_examples/threshold_ecdsa/src/index.ts
+++ b/examples/motoko_examples/threshold_ecdsa/src/index.ts
@@ -37,7 +37,7 @@ export default Canister({
     })
 });
 
-async function getPublicKeyResult() {
+async function getPublicKeyResult(): Promise<any> {
     const caller = ic.caller().toUint8Array();
 
     if (process.env.AZLE_TEST_FETCH === 'true') {
@@ -76,7 +76,7 @@ async function getPublicKeyResult() {
     }
 }
 
-async function getSignatureResult(messageHash: Uint8Array) {
+async function getSignatureResult(messageHash: Uint8Array): Promise<any> {
     const caller = ic.caller().toUint8Array();
 
     if (process.env.AZLE_TEST_FETCH === 'true') {
diff --git a/examples/nest/src/app.controller.ts b/examples/nest/src/app.controller.ts
index dade5b8f43..ea727bcf9d 100644
--- a/examples/nest/src/app.controller.ts
+++ b/examples/nest/src/app.controller.ts
@@ -81,7 +81,7 @@ export class AppController {
     }
 
     @Get('express-response')
-    expressResponse(@Res() response: Response) {
+    expressResponse(@Res() response: Response): void {
         response.send('App Express Response');
     }
 }
diff --git a/examples/nest/src/cats/cats.controller.ts b/examples/nest/src/cats/cats.controller.ts
index 2b8f3a84a4..2852e9030a 100644
--- a/examples/nest/src/cats/cats.controller.ts
+++ b/examples/nest/src/cats/cats.controller.ts
@@ -81,7 +81,7 @@ export class CatsController {
     }
 
     @Get('express-response')
-    expressResponse(@Res() response: Response) {
+    expressResponse(@Res() response: Response): void {
         response.send('Cats Express Response');
     }
 }
diff --git a/examples/nest/src/dogs/dogs.controller.ts b/examples/nest/src/dogs/dogs.controller.ts
index d44b91768c..798a13be5b 100644
--- a/examples/nest/src/dogs/dogs.controller.ts
+++ b/examples/nest/src/dogs/dogs.controller.ts
@@ -81,7 +81,7 @@ export class DogsController {
     }
 
     @Get('express-response')
-    expressResponse(@Res() response: Response) {
+    expressResponse(@Res() response: Response): void {
         response.send('Dogs Express Response');
     }
 }
diff --git a/examples/nest/src/main.ts b/examples/nest/src/main.ts
index 3db76030f6..d2febf011d 100644
--- a/examples/nest/src/main.ts
+++ b/examples/nest/src/main.ts
@@ -3,7 +3,7 @@ import { NestExpressApplication } from '@nestjs/platform-express';
 
 import { AppModule } from './app.module';
 
-async function bootstrap() {
+async function bootstrap(): Promise<void> {
     const app = await NestFactory.create<NestExpressApplication>(AppModule);
     await app.listen(3000);
 }
diff --git a/examples/robust_imports/src/azle_coverage/index.ts b/examples/robust_imports/src/azle_coverage/index.ts
index 0d18503576..f469fe2d44 100644
--- a/examples/robust_imports/src/azle_coverage/index.ts
+++ b/examples/robust_imports/src/azle_coverage/index.ts
@@ -95,7 +95,7 @@ export const Watermelon = Voavanga({
 
 let soncoya = Soncoya<nectarine8, PreparedFruit>(0);
 
-function gatherGrapes() {
+function gatherGrapes(): void {
     const opt = soncoya.get(0);
 
     if ('None' in opt) {
diff --git a/examples/robust_imports/src/type_alias_decls/index.ts b/examples/robust_imports/src/type_alias_decls/index.ts
index ba2df15f03..e8cc584cd6 100644
--- a/examples/robust_imports/src/type_alias_decls/index.ts
+++ b/examples/robust_imports/src/type_alias_decls/index.ts
@@ -2,7 +2,7 @@ import * as azle from 'azle/experimental';
 
 import * as types from './types';
 
-function offDuty() {}
+function offDuty(): void {}
 
 const HELLO_WORLD = 'Hello, World!';
 
diff --git a/examples/sqlite/src/entities/posts/router.ts b/examples/sqlite/src/entities/posts/router.ts
index 731fc1d5c8..3626e417d3 100644
--- a/examples/sqlite/src/entities/posts/router.ts
+++ b/examples/sqlite/src/entities/posts/router.ts
@@ -105,7 +105,7 @@ function updateHandler(
         { id: number; user_id?: number; title?: string; body?: string }
     >,
     res: Response
-) {
+): void {
     const { id, user_id, title, body } = req.body;
 
     const post = updatePost(db, {
diff --git a/examples/sqlite/src/entities/users/router.ts b/examples/sqlite/src/entities/users/router.ts
index 3fa8e5fde4..c232caf066 100644
--- a/examples/sqlite/src/entities/users/router.ts
+++ b/examples/sqlite/src/entities/users/router.ts
@@ -88,7 +88,7 @@ export function getRouter(): Router {
 function updateHandler(
     req: Request<any, any, { id: number; username?: string; age?: number }>,
     res: Response
-) {
+): void {
     const { id, username, age } = req.body;
 
     const user = updateUser(db, {
diff --git a/examples/sqlite_drizzle/src/entities/users/router.ts b/examples/sqlite_drizzle/src/entities/users/router.ts
index d92f0f768a..7b2bf5479b 100644
--- a/examples/sqlite_drizzle/src/entities/users/router.ts
+++ b/examples/sqlite_drizzle/src/entities/users/router.ts
@@ -91,7 +91,7 @@ export function getRouter(): Router {
 async function updateHandler(
     req: Request<any, any, { id: number; username?: string; age?: number }>,
     res: Response
-) {
+): Promise<void> {
     const { id, username, age } = req.body;
 
     const user = await updateUser(drizzleDb, {
diff --git a/examples/sqlite_typeorm/src/entities/posts/router.ts b/examples/sqlite_typeorm/src/entities/posts/router.ts
index 8908abe07d..a9b29b426a 100644
--- a/examples/sqlite_typeorm/src/entities/posts/router.ts
+++ b/examples/sqlite_typeorm/src/entities/posts/router.ts
@@ -109,7 +109,7 @@ async function updateHandler(
         { id: number; user_id?: number; title?: string; body?: string }
     >,
     res: Response
-) {
+): Promise<void> {
     const { id, user_id, title, body } = req.body;
 
     const post = await updatePost({
diff --git a/examples/sqlite_typeorm/src/entities/users/router.ts b/examples/sqlite_typeorm/src/entities/users/router.ts
index 7b956b2eb8..4abd3dfeef 100644
--- a/examples/sqlite_typeorm/src/entities/users/router.ts
+++ b/examples/sqlite_typeorm/src/entities/users/router.ts
@@ -90,7 +90,7 @@ export function getRouter(): Router {
 async function updateHandler(
     req: Request<any, any, { id: number; username?: string; age?: number }>,
     res: Response
-) {
+): Promise<void> {
     const { id, username, age } = req.body;
 
     const user = await updateUser({
diff --git a/examples/tfjs/src/api.ts b/examples/tfjs/src/api.ts
index eb99acf0d4..90338f6c7e 100644
--- a/examples/tfjs/src/api.ts
+++ b/examples/tfjs/src/api.ts
@@ -2,7 +2,7 @@ import * as tf from '@tensorflow/tfjs';
 import { ic } from 'azle/experimental';
 import express from 'express';
 
-async function init() {
+async function init(): Promise<void> {
     const app = express();
 
     app.use(express.json());
diff --git a/examples/timers/src/timers.ts b/examples/timers/src/timers.ts
index 4de85f814b..6ea0fdc42b 100644
--- a/examples/timers/src/timers.ts
+++ b/examples/timers/src/timers.ts
@@ -91,18 +91,18 @@ export default Canister({
     })
 });
 
-function oneTimeTimerCallback() {
+function oneTimeTimerCallback(): void {
     statusReport.single = true;
     console.log('oneTimeTimerCallback called');
 }
 
-async function singleCrossCanisterTimerCallback() {
+async function singleCrossCanisterTimerCallback(): Promise<void> {
     console.log('singleCrossCanisterTimerCallback');
 
     statusReport.singleCrossCanister = await getRandomness();
 }
 
-async function repeatCrossCanisterTimerCallback() {
+async function repeatCrossCanisterTimerCallback(): Promise<void> {
     console.log('repeatCrossCanisterTimerCallback');
 
     statusReport.repeatCrossCanister = Uint8Array.from([
diff --git a/examples/vanilla_js/src/library.js b/examples/vanilla_js/src/library.js
index 231e6cc303..e56f6fbbfa 100644
--- a/examples/vanilla_js/src/library.js
+++ b/examples/vanilla_js/src/library.js
@@ -1,3 +1,4 @@
+/* eslint-disable @typescript-eslint/explicit-function-return-type */
 export function relativeImport() {
     return 'relative import';
 }
diff --git a/http_client/fetch_ic/call.ts b/http_client/fetch_ic/call.ts
index 4cd7d649b9..aa3c20e01e 100644
--- a/http_client/fetch_ic/call.ts
+++ b/http_client/fetch_ic/call.ts
@@ -237,7 +237,7 @@ async function callHttpRequestUpdate(
     });
 }
 
-function checkGetHeadBody(method: string, body: Uint8Array) {
+function checkGetHeadBody(method: string, body: Uint8Array): void {
     if (
         (method.toLowerCase() === 'get' || method.toLowerCase() === 'head') &&
         body.length !== 0
diff --git a/http_client/fetch_ic/index.ts b/http_client/fetch_ic/index.ts
index 971f0fff8a..1f750371f2 100644
--- a/http_client/fetch_ic/index.ts
+++ b/http_client/fetch_ic/index.ts
@@ -42,7 +42,7 @@ export { createAgent } from './agent';
 export { getCanisterId };
 export { getHost } from './host';
 
-function logWarnings(init?: RequestInit | undefined) {
+function logWarnings(init?: RequestInit | undefined): void {
     if (init === undefined) {
         return;
     }
@@ -88,7 +88,7 @@ function logWarnings(init?: RequestInit | undefined) {
     }
 }
 
-function logWarning(method: string) {
+function logWarning(method: string): void {
     console.warn(
         `fetchIc: init.${method} has no effect when using an identity as the Authorization header`
     );
diff --git a/property_tests/arbitraries/candid/constructed/tuple_arb/definition_arb.ts b/property_tests/arbitraries/candid/constructed/tuple_arb/definition_arb.ts
index f27206ae02..210e2403f6 100644
--- a/property_tests/arbitraries/candid/constructed/tuple_arb/definition_arb.ts
+++ b/property_tests/arbitraries/candid/constructed/tuple_arb/definition_arb.ts
@@ -100,7 +100,7 @@ function generateCandidTypeAnnotation(
     useTypeDeclaration: boolean,
     name: string,
     fields: CandidDefinition[]
-) {
+): string {
     if (useTypeDeclaration === true) {
         return `typeof ${name}.tsType`;
     }
@@ -116,7 +116,7 @@ function generateCandidTypeObject(
     useTypeDeclaration: boolean,
     name: string,
     fields: CandidDefinition[]
-) {
+): string {
     if (useTypeDeclaration === true) {
         return name;
     }
diff --git a/property_tests/arbitraries/candid/constructed/tuple_arb/values_arbs.ts b/property_tests/arbitraries/candid/constructed/tuple_arb/values_arbs.ts
index d1c578382b..3c5dba54d3 100644
--- a/property_tests/arbitraries/candid/constructed/tuple_arb/values_arbs.ts
+++ b/property_tests/arbitraries/candid/constructed/tuple_arb/values_arbs.ts
@@ -54,7 +54,9 @@ function generateAgentResponseValue(
     return fields.map((field) => field.agentResponseValue);
 }
 
-function generateValueLiteral(fields: CandidValues<CorrespondingJSType>[]) {
+function generateValueLiteral(
+    fields: CandidValues<CorrespondingJSType>[]
+): string {
     const fieldLiterals = fields.map((field) => field.valueLiteral).join(',\n');
 
     return `[
diff --git a/property_tests/arbitraries/candid/constructed/vec_arb/values_arb.ts b/property_tests/arbitraries/candid/constructed/vec_arb/values_arb.ts
index 219da1c092..5881feee59 100644
--- a/property_tests/arbitraries/candid/constructed/vec_arb/values_arb.ts
+++ b/property_tests/arbitraries/candid/constructed/vec_arb/values_arb.ts
@@ -106,7 +106,7 @@ function generateValue<T extends CorrespondingJSType>(
 function generateValueLiteral<T extends CorrespondingJSType>(
     sample: CandidValues<T>[],
     innerCandidType: CandidType
-) {
+): string {
     const valueLiterals = sample.map((sample) => sample.valueLiteral).join(',');
 
     const valueLiteral = `[${valueLiterals}]`;
diff --git a/property_tests/arbitraries/candid/primitive/ints/index.ts b/property_tests/arbitraries/candid/primitive/ints/index.ts
index ea841d9a47..3dbe67383e 100644
--- a/property_tests/arbitraries/candid/primitive/ints/index.ts
+++ b/property_tests/arbitraries/candid/primitive/ints/index.ts
@@ -1,4 +1,4 @@
 import fc from 'fast-check';
 
-export const NumberArb = (depthLevel: number) =>
+export const NumberArb = (depthLevel: number): fc.Arbitrary<number> =>
     fc.bigIntN(depthLevel).map((value) => Number(value));
diff --git a/property_tests/arbitraries/candid/primitive/nats/index.ts b/property_tests/arbitraries/candid/primitive/nats/index.ts
index 9382ba994d..e40ebc2a85 100644
--- a/property_tests/arbitraries/candid/primitive/nats/index.ts
+++ b/property_tests/arbitraries/candid/primitive/nats/index.ts
@@ -1,4 +1,4 @@
 import fc from 'fast-check';
 
-export const UNumberArb = (depthLevel: number) =>
+export const UNumberArb = (depthLevel: number): fc.Arbitrary<number> =>
     fc.bigUintN(depthLevel).map((value) => Number(value));
diff --git a/property_tests/arbitraries/candid/reference/principal_arb.ts b/property_tests/arbitraries/candid/reference/principal_arb.ts
index 7bd64dbce9..fd3412cb2a 100644
--- a/property_tests/arbitraries/candid/reference/principal_arb.ts
+++ b/property_tests/arbitraries/candid/reference/principal_arb.ts
@@ -27,7 +27,7 @@ export function PrincipalValueArb(): fc.Arbitrary<CandidValues<Principal>> {
     return SimpleCandidValuesArb(principal(), principalToSrcLiteral);
 }
 
-function principal() {
+function principal(): fc.Arbitrary<Principal> {
     return fc
         .uint8Array({
             minLength: 29,
diff --git a/property_tests/arbitraries/candid/reference/service_arb/definition_arb.ts b/property_tests/arbitraries/candid/reference/service_arb/definition_arb.ts
index ae8718c9e5..b8dbf596c4 100644
--- a/property_tests/arbitraries/candid/reference/service_arb/definition_arb.ts
+++ b/property_tests/arbitraries/candid/reference/service_arb/definition_arb.ts
@@ -106,7 +106,7 @@ function generateVariableAliasDeclarations(
 function generateCandidTypeAnnotation(
     useTypeDeclaration: boolean,
     name: string
-) {
+): string {
     if (useTypeDeclaration === true) {
         return `typeof ${name}.tsType`;
     }
@@ -118,7 +118,7 @@ function generateCandidTypeObject(
     useTypeDeclaration: boolean,
     name: string,
     serviceMethods: ServiceMethodDefinition[]
-) {
+): string {
     if (useTypeDeclaration === true) {
         return name;
     }
diff --git a/property_tests/arbitraries/candid/reference/service_arb/service_method_arb.ts b/property_tests/arbitraries/candid/reference/service_arb/service_method_arb.ts
index 2b3c20d96d..eb567e4566 100644
--- a/property_tests/arbitraries/candid/reference/service_arb/service_method_arb.ts
+++ b/property_tests/arbitraries/candid/reference/service_arb/service_method_arb.ts
@@ -93,7 +93,7 @@ function generateRuntimeCandidTypeObject(
     mode: Mode,
     params: CandidDefinition[],
     returnType: CandidDefinition
-) {
+): CanisterMethodInfo<CandidType[], CandidType> {
     const queryOrUpdate = mode === 'query' ? query : update;
     const paramCandidTypeObjects = params.map(
         (param) => param.candidMeta.runtimeCandidTypeObject
diff --git a/property_tests/arbitraries/candid/to_src_literal/string.ts b/property_tests/arbitraries/candid/to_src_literal/string.ts
index 54f4682739..6e30745e24 100644
--- a/property_tests/arbitraries/candid/to_src_literal/string.ts
+++ b/property_tests/arbitraries/candid/to_src_literal/string.ts
@@ -1,4 +1,4 @@
-function escapeStringForJavaScript(input: string) {
+function escapeStringForJavaScript(input: string): string {
     return input
         .replace(/\\/g, '\\\\') // Escape backslashes
         .replace(/'/g, "\\'") // Escape single quotes
diff --git a/property_tests/arbitraries/canister_arb.ts b/property_tests/arbitraries/canister_arb.ts
index 170170a198..57ea2f42dc 100644
--- a/property_tests/arbitraries/canister_arb.ts
+++ b/property_tests/arbitraries/canister_arb.ts
@@ -52,7 +52,7 @@ export function CanisterArb<
     configArb: fc.Arbitrary<
         CanisterConfig<ParamAgentArgumentValue, ParamAgentResponseValue>
     >
-) {
+): fc.Arbitrary<Canister> {
     return configArb.map((config): Canister => {
         const canisterMethods: CanisterMethod<
             ParamAgentArgumentValue,
@@ -128,7 +128,7 @@ export function CanisterArb<
 function generateSourceCode(
     globalDeclarations: string[],
     canisterMethods: (UpdateMethod | QueryMethod)[]
-) {
+): string {
     const imports = [
         ...new Set([
             'Canister',
diff --git a/property_tests/arbitraries/canister_methods/inspect_message_method_arb.ts b/property_tests/arbitraries/canister_methods/inspect_message_method_arb.ts
index 8b17f4675d..ba200f3b55 100644
--- a/property_tests/arbitraries/canister_methods/inspect_message_method_arb.ts
+++ b/property_tests/arbitraries/canister_methods/inspect_message_method_arb.ts
@@ -22,7 +22,7 @@ export function InspectMessageMethodArb(constraints: {
     generateBody: BodyGenerator;
     generateTests: TestsGenerator;
     callbackLocation?: CallbackLocation;
-}) {
+}): fc.Arbitrary<InspectMessageMethod> {
     return fc
         .tuple(
             UniqueIdentifierArb('canisterProperties'),
diff --git a/property_tests/arbitraries/canister_methods/pre_upgrade_method_arb.ts b/property_tests/arbitraries/canister_methods/pre_upgrade_method_arb.ts
index c974eecc7f..e651e1a5ae 100644
--- a/property_tests/arbitraries/canister_methods/pre_upgrade_method_arb.ts
+++ b/property_tests/arbitraries/canister_methods/pre_upgrade_method_arb.ts
@@ -22,7 +22,7 @@ export function PreUpgradeMethodArb(constraints: {
     generateBody: BodyGenerator;
     generateTests: TestsGenerator;
     callbackLocation?: CallbackLocation;
-}) {
+}): fc.Arbitrary<PreUpgradeMethod> {
     return fc
         .tuple(
             UniqueIdentifierArb('canisterProperties'),
diff --git a/property_tests/arbitraries/canister_methods/query_method_arb.ts b/property_tests/arbitraries/canister_methods/query_method_arb.ts
index 76b3055ed6..ea443c5d1b 100644
--- a/property_tests/arbitraries/canister_methods/query_method_arb.ts
+++ b/property_tests/arbitraries/canister_methods/query_method_arb.ts
@@ -53,7 +53,7 @@ export function QueryMethodArb<
         callbackLocation?: CallbackLocation;
         name?: string;
     }
-) {
+): fc.Arbitrary<QueryMethod> {
     return fc
         .tuple(
             UniqueIdentifierArb('canisterProperties'),
diff --git a/property_tests/arbitraries/canister_methods/update_method_arb.ts b/property_tests/arbitraries/canister_methods/update_method_arb.ts
index edb32286cf..d590d7edd0 100644
--- a/property_tests/arbitraries/canister_methods/update_method_arb.ts
+++ b/property_tests/arbitraries/canister_methods/update_method_arb.ts
@@ -52,7 +52,7 @@ export function UpdateMethodArb<
         callbackLocation?: CallbackLocation;
         name?: string;
     }
-) {
+): fc.Arbitrary<UpdateMethod> {
     return fc
         .tuple(
             UniqueIdentifierArb('canisterProperties'),
diff --git a/property_tests/arbitraries/http/body_arb.ts b/property_tests/arbitraries/http/body_arb.ts
index ae8a711cb6..c863bf5d78 100644
--- a/property_tests/arbitraries/http/body_arb.ts
+++ b/property_tests/arbitraries/http/body_arb.ts
@@ -1,5 +1,5 @@
 import fc from 'fast-check';
 
-export function BodyArb() {
+export function BodyArb(): fc.Arbitrary<Uint8Array> {
     return fc.json().map((json) => new Uint8Array(Buffer.from(json, 'utf-8')));
 }
diff --git a/property_tests/arbitraries/http/headers_arb.ts b/property_tests/arbitraries/http/headers_arb.ts
index 413f7c54f5..c32fab4d4f 100644
--- a/property_tests/arbitraries/http/headers_arb.ts
+++ b/property_tests/arbitraries/http/headers_arb.ts
@@ -4,7 +4,7 @@ import fc from 'fast-check';
 
 const RESERVED_HEADERS = ['__proto__'];
 
-export function HttpHeadersArb() {
+export function HttpHeadersArb(): fc.Arbitrary<[string, string][]> {
     const HeaderNameArb = fc
         .stringMatching(/^[a-zA-Z0-9_-]+$/)
         .filter((name) => !RESERVED_HEADERS.includes(name));
diff --git a/property_tests/arbitraries/http/response_arb.ts b/property_tests/arbitraries/http/response_arb.ts
index a029b4da8d..2ccc937b24 100644
--- a/property_tests/arbitraries/http/response_arb.ts
+++ b/property_tests/arbitraries/http/response_arb.ts
@@ -39,7 +39,7 @@ const StatusCodeArb = fc
 // TODO same applies to 421 status see https://github.com/demergent-labs/fourZeroSeven for more details
 // TODO https://github.com/nodejs/help/issues/4345
 
-export function HttpResponseValueArb<T>() {
+export function HttpResponseValueArb<T>(): fc.Arbitrary<HttpResponse<T>> {
     return fc
         .tuple(StatusCodeArb, HttpHeadersArb())
         .chain(([statusCode, headers]) => {
diff --git a/property_tests/arbitraries/unique_identifier_arb.ts b/property_tests/arbitraries/unique_identifier_arb.ts
index 49e261bc0a..566fec1d85 100644
--- a/property_tests/arbitraries/unique_identifier_arb.ts
+++ b/property_tests/arbitraries/unique_identifier_arb.ts
@@ -1,3 +1,5 @@
+import fc from 'fast-check';
+
 import { JsFunctionNameArb } from './js_function_name_arb';
 
 type IdentifiersMap = {
@@ -13,7 +15,7 @@ let identifiers: IdentifiersMap = {};
  * @param key the grouping in which to keep this identifier unique
  * @returns an arbitrary identifier string
  */
-export function UniqueIdentifierArb(key: string) {
+export function UniqueIdentifierArb(key: string): fc.Arbitrary<string> {
     if (!(key in identifiers)) {
         identifiers[key] = new Set();
     }
diff --git a/property_tests/arbitraries/unique_primitive_arb.ts b/property_tests/arbitraries/unique_primitive_arb.ts
index 79199d1c25..cc9c5264f6 100644
--- a/property_tests/arbitraries/unique_primitive_arb.ts
+++ b/property_tests/arbitraries/unique_primitive_arb.ts
@@ -4,7 +4,9 @@ import fc from 'fast-check';
 // TODO this doesn't seem right, instead I think they should pass in a set of their own
 let samples = new Set();
 
-export function createUniquePrimitiveArb<T>(arb: fc.Arbitrary<T>) {
+export function createUniquePrimitiveArb<T>(
+    arb: fc.Arbitrary<T>
+): fc.Arbitrary<T> {
     return arb
         .filter((primitiveSample) => !samples.has(primitiveSample))
         .map((primitiveSample) => {
@@ -13,6 +15,6 @@ export function createUniquePrimitiveArb<T>(arb: fc.Arbitrary<T>) {
         });
 }
 
-export function clear() {
+export function clear(): void {
     samples = new Set();
 }
diff --git a/property_tests/are_params_correctly_ordered.ts b/property_tests/are_params_correctly_ordered.ts
index f8d616e4be..e239a3b5d7 100644
--- a/property_tests/are_params_correctly_ordered.ts
+++ b/property_tests/are_params_correctly_ordered.ts
@@ -4,7 +4,7 @@ import { CorrespondingJSType } from './arbitraries/candid/corresponding_js_type'
 
 export function areParamsCorrectlyOrdered<T extends CorrespondingJSType>(
     params: Named<CandidValueAndMeta<T>>[]
-) {
+): string {
     return params
         .map(({ name, value }) => {
             const areEqual = `deepEqual(
diff --git a/property_tests/get_actor.ts b/property_tests/get_actor.ts
index 3d8c3b83b9..69f700e358 100644
--- a/property_tests/get_actor.ts
+++ b/property_tests/get_actor.ts
@@ -2,7 +2,7 @@ import { Agent, HttpAgent } from '@dfinity/agent';
 
 import { getCanisterId } from '../dfx';
 
-export function getActor(parentDir: string, agent?: Agent) {
+export function getActor(parentDir: string, agent?: Agent): any {
     const resolvedPathIndex = require.resolve(
         `${parentDir}/dfx_generated/canister/index.js`
     );
diff --git a/property_tests/index.ts b/property_tests/index.ts
index d664f9e190..2926674e2e 100644
--- a/property_tests/index.ts
+++ b/property_tests/index.ts
@@ -18,7 +18,7 @@ export { getActor } from './get_actor';
 export async function runPropTests(
     canisterArb: fc.Arbitrary<Canister>,
     runTestsSeparately = false
-) {
+): Promise<void> {
     const defaultParams = {
         numRuns: runTestsSeparately
             ? 1
diff --git a/property_tests/test/index.ts b/property_tests/test/index.ts
index 8a385814c7..d2a009265a 100644
--- a/property_tests/test/index.ts
+++ b/property_tests/test/index.ts
@@ -15,7 +15,7 @@ export type Test<> = {
 };
 
 // TODO get rid of this union once the jest migration is complete
-type AzleResult =
+export type AzleResult =
     | Partial<{
           Ok: { isSuccessful: boolean; message?: string };
           Err: string;
@@ -169,7 +169,7 @@ export function createSnakeCaseProxy<T extends object>(
     }
 
     return new Proxy(target, {
-        get(obj, prop) {
+        get(obj, prop): any {
             const snakeCaseProp =
                 (prop as string)[0] === (prop as string)[0]?.toUpperCase()
                     ? prop
@@ -240,6 +240,6 @@ function convertKeysToSnakeCase(obj: any): any {
     return newObj;
 }
 
-function camelToSnakeCase(str: string) {
+function camelToSnakeCase(str: string): string {
     return str.replace(/[A-Z]/g, (letter) => `_${letter.toLowerCase()}`);
 }
diff --git a/property_tests/tests/blob/test/generate_tests.ts b/property_tests/tests/blob/test/generate_tests.ts
index 67836443d1..7a40235d34 100644
--- a/property_tests/tests/blob/test/generate_tests.ts
+++ b/property_tests/tests/blob/test/generate_tests.ts
@@ -1,6 +1,6 @@
 import { getActor, Named } from 'azle/property_tests';
 import { CandidValueAndMeta } from 'azle/property_tests/arbitraries/candid/candid_value_and_meta_arb';
-import { Test, testEquality } from 'azle/property_tests/test';
+import { AzleResult, Test, testEquality } from 'azle/property_tests/test';
 
 export function generateTests(
     functionName: string,
@@ -20,7 +20,7 @@ export function generateTests(
         [
             {
                 name: `blob ${functionName}`,
-                test: async () => {
+                test: async (): Promise<AzleResult> => {
                     const actor = getActor(__dirname);
 
                     const result = await actor[functionName](
diff --git a/property_tests/tests/bool/test/generate_tests.ts b/property_tests/tests/bool/test/generate_tests.ts
index 9a6438982a..a91e7cc3b6 100644
--- a/property_tests/tests/bool/test/generate_tests.ts
+++ b/property_tests/tests/bool/test/generate_tests.ts
@@ -1,6 +1,6 @@
 import { getActor, Named } from 'azle/property_tests';
 import { CandidValueAndMeta } from 'azle/property_tests/arbitraries/candid/candid_value_and_meta_arb';
-import { Test, testEquality } from 'azle/property_tests/test';
+import { AzleResult, Test, testEquality } from 'azle/property_tests/test';
 
 export function generateTests(
     functionName: string,
@@ -19,7 +19,7 @@ export function generateTests(
         [
             {
                 name: `bool ${functionName}`,
-                test: async () => {
+                test: async (): Promise<AzleResult> => {
                     const actor = getActor(__dirname);
 
                     const result = await actor[functionName](...paramValues);
diff --git a/property_tests/tests/canister_methods/http_request/test/fletch.ts b/property_tests/tests/canister_methods/http_request/test/fletch.ts
index efaa9c4554..24f1694059 100644
--- a/property_tests/tests/canister_methods/http_request/test/fletch.ts
+++ b/property_tests/tests/canister_methods/http_request/test/fletch.ts
@@ -65,7 +65,7 @@ export function fletchSync(canisterName: string, options: HttpRequest) {
     return toResponseSync(responseBuffer);
 }
 
-function escapeForExecSync(input: string) {
+function escapeForExecSync(input: string): string {
     return input
         .replace(/\\/g, '\\\\') // Escape backslashes
         .replace(/"/g, '\\"') // Escape double quotes
@@ -73,13 +73,13 @@ function escapeForExecSync(input: string) {
         .replace(/\$/g, '\\$'); // Escape dollar signs
 }
 
-function toCurlHeadersString(headers: [string, string][]) {
+function toCurlHeadersString(headers: [string, string][]): string {
     return headers
         .map(([name, value]) => `-H ${singleQuotedString(`${name}: ${value}`)}`)
         .join(' ');
 }
 
-function singleQuotedString(input: string) {
+function singleQuotedString(input: string): string {
     const singleQuoteEscapedString = input.replace(/'/g, "'\\''");
 
     return `'${singleQuoteEscapedString}'`;
diff --git a/property_tests/tests/canister_methods/http_request/test/generate_body.ts b/property_tests/tests/canister_methods/http_request/test/generate_body.ts
index 9b36cc5b41..b18e3df773 100644
--- a/property_tests/tests/canister_methods/http_request/test/generate_body.ts
+++ b/property_tests/tests/canister_methods/http_request/test/generate_body.ts
@@ -32,7 +32,10 @@ export function generateBody(
     `;
 }
 
-function generateHttpMethodCheck(method: string, requestParamName: string) {
+function generateHttpMethodCheck(
+    method: string,
+    requestParamName: string
+): string {
     return `
         if (${requestParamName}.method !== '${method}') {
             throw new Error(
@@ -42,7 +45,7 @@ function generateHttpMethodCheck(method: string, requestParamName: string) {
     `;
 }
 
-function generateUrlCheck(url: string, requestParamName: string) {
+function generateUrlCheck(url: string, requestParamName: string): string {
     return `
         if (decodeURIComponent(${requestParamName}.url) !== decodeURIComponent('${escape(
             url
@@ -59,7 +62,7 @@ function generateUrlCheck(url: string, requestParamName: string) {
 function generateHeadersMap(
     headers: [string, string][],
     requestParamName: string
-) {
+): string {
     return headers.length === 0
         ? ''
         : `
@@ -69,7 +72,7 @@ function generateHeadersMap(
         `;
 }
 
-function generateHeaderChecks(headers: [string, string][]) {
+function generateHeaderChecks(headers: [string, string][]): string {
     return headers
         .map(([name, value]) => {
             if (value === '') {
@@ -80,7 +83,7 @@ function generateHeaderChecks(headers: [string, string][]) {
         .join('\n');
 }
 
-function generateEmptyHeaderCheck(name: string) {
+function generateEmptyHeaderCheck(name: string): string {
     return `if (headers['${escape(
         name
     ).toLowerCase()}'] !== undefined && headers['${escape(
@@ -124,7 +127,7 @@ function generateBodyCheck(body: Uint8Array, requestParamName: string): string {
     }`;
 }
 
-function escape(input: string) {
+function escape(input: string): string {
     return input
         .replace(/\\/g, '\\\\') // Escape backslashes
         .replace(/\$\{/g, '\\${') // Escape interpolation starts
diff --git a/property_tests/tests/canister_methods/http_request/test/generate_tests.ts b/property_tests/tests/canister_methods/http_request/test/generate_tests.ts
index 84cda17fa2..cc66fcf5ca 100644
--- a/property_tests/tests/canister_methods/http_request/test/generate_tests.ts
+++ b/property_tests/tests/canister_methods/http_request/test/generate_tests.ts
@@ -2,7 +2,7 @@ import { HttpRequest, HttpResponse } from 'azle/experimental';
 import { Named } from 'azle/property_tests';
 import { CandidValueAndMeta } from 'azle/property_tests/arbitraries/candid/candid_value_and_meta_arb';
 import { HttpResponseAgentResponseValue } from 'azle/property_tests/arbitraries/http/response_arb';
-import { Test, testEquality } from 'azle/property_tests/test';
+import { AzleResult, Test, testEquality } from 'azle/property_tests/test';
 
 import { fletch } from './fletch';
 
@@ -21,7 +21,7 @@ export function generateTests(
         [
             {
                 name: functionName,
-                test: async () => {
+                test: async (): Promise<AzleResult> => {
                     const response = await fletch('canister', request);
                     const filteredHeaders = response.headers
                         .filter(
diff --git a/property_tests/tests/canister_methods/http_request_update/test/fletch.ts b/property_tests/tests/canister_methods/http_request_update/test/fletch.ts
index efaa9c4554..24f1694059 100644
--- a/property_tests/tests/canister_methods/http_request_update/test/fletch.ts
+++ b/property_tests/tests/canister_methods/http_request_update/test/fletch.ts
@@ -65,7 +65,7 @@ export function fletchSync(canisterName: string, options: HttpRequest) {
     return toResponseSync(responseBuffer);
 }
 
-function escapeForExecSync(input: string) {
+function escapeForExecSync(input: string): string {
     return input
         .replace(/\\/g, '\\\\') // Escape backslashes
         .replace(/"/g, '\\"') // Escape double quotes
@@ -73,13 +73,13 @@ function escapeForExecSync(input: string) {
         .replace(/\$/g, '\\$'); // Escape dollar signs
 }
 
-function toCurlHeadersString(headers: [string, string][]) {
+function toCurlHeadersString(headers: [string, string][]): string {
     return headers
         .map(([name, value]) => `-H ${singleQuotedString(`${name}: ${value}`)}`)
         .join(' ');
 }
 
-function singleQuotedString(input: string) {
+function singleQuotedString(input: string): string {
     const singleQuoteEscapedString = input.replace(/'/g, "'\\''");
 
     return `'${singleQuoteEscapedString}'`;
diff --git a/property_tests/tests/canister_methods/http_request_update/test/generate_body.ts b/property_tests/tests/canister_methods/http_request_update/test/generate_body.ts
index bfd9012930..9eb54a1e56 100644
--- a/property_tests/tests/canister_methods/http_request_update/test/generate_body.ts
+++ b/property_tests/tests/canister_methods/http_request_update/test/generate_body.ts
@@ -34,7 +34,10 @@ export function generateBody(
     `;
 }
 
-function generateHttpMethodCheck(method: string, requestParamName: string) {
+function generateHttpMethodCheck(
+    method: string,
+    requestParamName: string
+): string {
     return `
         if (${requestParamName}.method !== '${method}') {
             throw new Error(
@@ -44,7 +47,7 @@ function generateHttpMethodCheck(method: string, requestParamName: string) {
     `;
 }
 
-function generateUrlCheck(url: string, requestParamName: string) {
+function generateUrlCheck(url: string, requestParamName: string): string {
     return `
         if (decodeURIComponent(${requestParamName}.url) !== decodeURIComponent('${escape(
             url
@@ -61,7 +64,7 @@ function generateUrlCheck(url: string, requestParamName: string) {
 function generateHeadersMap(
     headers: [string, string][],
     requestParamName: string
-) {
+): string {
     return headers.length === 0
         ? ''
         : `
@@ -71,7 +74,7 @@ function generateHeadersMap(
         `;
 }
 
-function generateHeaderChecks(headers: [string, string][]) {
+function generateHeaderChecks(headers: [string, string][]): string {
     return headers
         .map(([name, value]) => {
             if (value === '') {
@@ -82,7 +85,7 @@ function generateHeaderChecks(headers: [string, string][]) {
         .join('\n');
 }
 
-function generateEmptyHeaderCheck(name: string) {
+function generateEmptyHeaderCheck(name: string): string {
     return `if (headers['${escape(
         name
     ).toLowerCase()}'] !== undefined && headers['${escape(
@@ -126,7 +129,7 @@ function generateBodyCheck(body: Uint8Array, requestParamName: string): string {
     }`;
 }
 
-function escape(input: string) {
+function escape(input: string): string {
     return input
         .replace(/\\/g, '\\\\') // Escape backslashes
         .replace(/\$\{/g, '\\${') // Escape interpolation starts
diff --git a/property_tests/tests/canister_methods/http_request_update/test/generate_tests.ts b/property_tests/tests/canister_methods/http_request_update/test/generate_tests.ts
index 17ec2631ea..edbe45fb6e 100644
--- a/property_tests/tests/canister_methods/http_request_update/test/generate_tests.ts
+++ b/property_tests/tests/canister_methods/http_request_update/test/generate_tests.ts
@@ -2,7 +2,7 @@ import { HttpRequest, HttpResponse } from 'azle/experimental';
 import { getActor, Named } from 'azle/property_tests';
 import { CandidValueAndMeta } from 'azle/property_tests/arbitraries/candid/candid_value_and_meta_arb';
 import { HttpResponseAgentResponseValue } from 'azle/property_tests/arbitraries/http/response_arb';
-import { Test, testEquality } from 'azle/property_tests/test';
+import { AzleResult, Test, testEquality } from 'azle/property_tests/test';
 
 import { fletch } from './fletch';
 
@@ -21,7 +21,7 @@ export function generateTests(
         [
             {
                 name: 'get state before calling http_request',
-                test: async () => {
+                test: async (): Promise<AzleResult> => {
                     const actor = getActor(__dirname);
 
                     const result = await actor['get_state']();
@@ -31,7 +31,7 @@ export function generateTests(
             },
             {
                 name: functionName,
-                test: async () => {
+                test: async (): Promise<AzleResult> => {
                     const response = await fletch('canister', request);
                     const filteredHeaders = response.headers
                         .filter(
@@ -61,7 +61,7 @@ export function generateTests(
             },
             {
                 name: 'get state after calling http_request',
-                test: async () => {
+                test: async (): Promise<AzleResult> => {
                     const actor = getActor(__dirname);
 
                     const result = await actor['get_state']();
diff --git a/property_tests/tests/canister_methods/init/test/generate_callable_method_body.ts b/property_tests/tests/canister_methods/init/test/generate_callable_method_body.ts
index 42b2e2f5df..d52e92001a 100644
--- a/property_tests/tests/canister_methods/init/test/generate_callable_method_body.ts
+++ b/property_tests/tests/canister_methods/init/test/generate_callable_method_body.ts
@@ -5,6 +5,6 @@ import { CorrespondingJSType } from 'azle/property_tests/arbitraries/candid/corr
 export function generateBody(
     _namedParams: Named<CandidValueAndMeta<CorrespondingJSType>>[],
     returnType: CandidValueAndMeta<CorrespondingJSType>
-) {
+): string {
     return `return ${returnType.src.valueLiteral}`;
 }
diff --git a/property_tests/tests/canister_methods/init/test/generate_init_body.ts b/property_tests/tests/canister_methods/init/test/generate_init_body.ts
index 47c4b8cb8e..d05ca5d40d 100644
--- a/property_tests/tests/canister_methods/init/test/generate_init_body.ts
+++ b/property_tests/tests/canister_methods/init/test/generate_init_body.ts
@@ -5,7 +5,7 @@ import { areParamsCorrectlyOrdered } from 'azle/property_tests/are_params_correc
 
 export function generateBody(
     namedParams: Named<CandidValueAndMeta<CorrespondingJSType>>[]
-) {
+): string {
     const paramsAreCorrectlyOrdered = areParamsCorrectlyOrdered(namedParams);
 
     const storeVariablesGlobally = namedParams
diff --git a/property_tests/tests/canister_methods/init/test/generate_tests.ts b/property_tests/tests/canister_methods/init/test/generate_tests.ts
index 7fbdd92f45..3d2c072716 100644
--- a/property_tests/tests/canister_methods/init/test/generate_tests.ts
+++ b/property_tests/tests/canister_methods/init/test/generate_tests.ts
@@ -1,7 +1,7 @@
 import { getActor, Named } from 'azle/property_tests';
 import { CandidValueAndMeta } from 'azle/property_tests/arbitraries/candid/candid_value_and_meta_arb';
 import { CorrespondingJSType } from 'azle/property_tests/arbitraries/candid/corresponding_js_type';
-import { Test, testEquality } from 'azle/property_tests/test';
+import { AzleResult, Test, testEquality } from 'azle/property_tests/test';
 
 export function generateTests(
     _functionName: string,
@@ -16,7 +16,7 @@ export function generateTests(
         [
             {
                 name: `init method`,
-                test: async () => {
+                test: async (): Promise<AzleResult> => {
                     const actor = getActor(__dirname);
                     const result = await actor.getInitValues();
 
diff --git a/property_tests/tests/canister_methods/inspect_message/test/generate_tests.ts b/property_tests/tests/canister_methods/inspect_message/test/generate_tests.ts
index 5dff24d0f9..aa93ddd6af 100644
--- a/property_tests/tests/canister_methods/inspect_message/test/generate_tests.ts
+++ b/property_tests/tests/canister_methods/inspect_message/test/generate_tests.ts
@@ -3,7 +3,7 @@ import { getActor, Named } from 'azle/property_tests';
 import { CandidReturnType } from 'azle/property_tests/arbitraries/candid/candid_return_type_arb';
 import { CandidValueAndMeta } from 'azle/property_tests/arbitraries/candid/candid_value_and_meta_arb';
 import { CorrespondingJSType } from 'azle/property_tests/arbitraries/candid/corresponding_js_type';
-import { Test, testEquality } from 'azle/property_tests/test';
+import { AzleResult, Test, testEquality } from 'azle/property_tests/test';
 
 import { InspectMessageBehavior } from './test';
 
@@ -41,7 +41,7 @@ function generateTest(
 ): Test {
     return {
         name: `method "${functionName}" expected ${behavior}`,
-        test: async () => {
+        test: async (): Promise<AzleResult> => {
             await agent.fetchRootKey();
             const actor = getActor(__dirname, agent);
             try {
diff --git a/property_tests/tests/canister_methods/post_upgrade/test/generate_callable_method_body.ts b/property_tests/tests/canister_methods/post_upgrade/test/generate_callable_method_body.ts
index 42b2e2f5df..d52e92001a 100644
--- a/property_tests/tests/canister_methods/post_upgrade/test/generate_callable_method_body.ts
+++ b/property_tests/tests/canister_methods/post_upgrade/test/generate_callable_method_body.ts
@@ -5,6 +5,6 @@ import { CorrespondingJSType } from 'azle/property_tests/arbitraries/candid/corr
 export function generateBody(
     _namedParams: Named<CandidValueAndMeta<CorrespondingJSType>>[],
     returnType: CandidValueAndMeta<CorrespondingJSType>
-) {
+): string {
     return `return ${returnType.src.valueLiteral}`;
 }
diff --git a/property_tests/tests/canister_methods/post_upgrade/test/generate_init_method_body.ts b/property_tests/tests/canister_methods/post_upgrade/test/generate_init_method_body.ts
index 3409c1e4ea..11ca50e9ac 100644
--- a/property_tests/tests/canister_methods/post_upgrade/test/generate_init_method_body.ts
+++ b/property_tests/tests/canister_methods/post_upgrade/test/generate_init_method_body.ts
@@ -7,7 +7,7 @@ import { globalInitVarName } from './global_var_name';
 
 export function generateBody(
     namedParams: Named<CandidValueAndMeta<CorrespondingJSType>>[]
-) {
+): string {
     const paramsAreCorrectlyOrdered = areParamsCorrectlyOrdered(namedParams);
 
     const storeVariablesGlobally = namedParams
diff --git a/property_tests/tests/canister_methods/post_upgrade/test/generate_init_tests.ts b/property_tests/tests/canister_methods/post_upgrade/test/generate_init_tests.ts
index 4104165fdb..c6633d557b 100644
--- a/property_tests/tests/canister_methods/post_upgrade/test/generate_init_tests.ts
+++ b/property_tests/tests/canister_methods/post_upgrade/test/generate_init_tests.ts
@@ -1,7 +1,7 @@
 import { getActor, Named } from 'azle/property_tests';
 import { CandidValueAndMeta } from 'azle/property_tests/arbitraries/candid/candid_value_and_meta_arb';
 import { CorrespondingJSType } from 'azle/property_tests/arbitraries/candid/corresponding_js_type';
-import { Test, testEquality } from 'azle/property_tests/test';
+import { AzleResult, Test, testEquality } from 'azle/property_tests/test';
 
 export function generateTests(
     _functionName: string,
@@ -16,7 +16,7 @@ export function generateTests(
         [
             {
                 name: `init method`,
-                test: async () => {
+                test: async (): Promise<AzleResult> => {
                     const actor = getActor(__dirname);
 
                     const initValues = await actor.getInitValues();
diff --git a/property_tests/tests/canister_methods/post_upgrade/test/generate_post_upgrade_method_body.ts b/property_tests/tests/canister_methods/post_upgrade/test/generate_post_upgrade_method_body.ts
index 82bedd05a6..53e2b3d832 100644
--- a/property_tests/tests/canister_methods/post_upgrade/test/generate_post_upgrade_method_body.ts
+++ b/property_tests/tests/canister_methods/post_upgrade/test/generate_post_upgrade_method_body.ts
@@ -7,7 +7,7 @@ import { globalPostUpgradeVarName } from './global_var_name';
 
 export function generateBody(
     namedParams: Named<CandidValueAndMeta<CorrespondingJSType>>[]
-) {
+): string {
     const paramsAreCorrectlyOrdered = areParamsCorrectlyOrdered(namedParams);
 
     const storeVariablesGlobally = namedParams
diff --git a/property_tests/tests/canister_methods/post_upgrade/test/generate_post_upgrade_tests.ts b/property_tests/tests/canister_methods/post_upgrade/test/generate_post_upgrade_tests.ts
index 929dee0a86..cafe9558b7 100644
--- a/property_tests/tests/canister_methods/post_upgrade/test/generate_post_upgrade_tests.ts
+++ b/property_tests/tests/canister_methods/post_upgrade/test/generate_post_upgrade_tests.ts
@@ -1,7 +1,7 @@
 import { getActor, Named } from 'azle/property_tests';
 import { CandidValueAndMeta } from 'azle/property_tests/arbitraries/candid/candid_value_and_meta_arb';
 import { CorrespondingJSType } from 'azle/property_tests/arbitraries/candid/corresponding_js_type';
-import { Test, testEquality } from 'azle/property_tests/test';
+import { AzleResult, Test, testEquality } from 'azle/property_tests/test';
 
 export function generateTests(
     _functionName: string,
@@ -17,7 +17,7 @@ export function generateTests(
         [
             {
                 name: `post upgrade method`,
-                test: async () => {
+                test: async (): Promise<AzleResult> => {
                     const actor = getActor(__dirname);
 
                     const postUpgradeValues =
diff --git a/property_tests/tests/canister_methods/post_upgrade/test/global_var_name.ts b/property_tests/tests/canister_methods/post_upgrade/test/global_var_name.ts
index 1b18abce87..11feddbcf4 100644
--- a/property_tests/tests/canister_methods/post_upgrade/test/global_var_name.ts
+++ b/property_tests/tests/canister_methods/post_upgrade/test/global_var_name.ts
@@ -1,7 +1,7 @@
-export function globalInitVarName(i: number) {
+export function globalInitVarName(i: number): string {
     return `initParam${i}`;
 }
 
-export function globalPostUpgradeVarName(i: number) {
+export function globalPostUpgradeVarName(i: number): string {
     return `postUpgradeParam${i}`;
 }
diff --git a/property_tests/tests/canister_methods/pre_upgrade/test/test.ts b/property_tests/tests/canister_methods/pre_upgrade/test/test.ts
index a976254a5d..35c4adb86a 100644
--- a/property_tests/tests/canister_methods/pre_upgrade/test/test.ts
+++ b/property_tests/tests/canister_methods/pre_upgrade/test/test.ts
@@ -12,7 +12,7 @@ import {
     QueryMethodArb
 } from 'azle/property_tests/arbitraries/canister_methods/query_method_arb';
 import { UpdateMethodArb } from 'azle/property_tests/arbitraries/canister_methods/update_method_arb';
-import { testEquality } from 'azle/property_tests/test';
+import { AzleResult, testEquality } from 'azle/property_tests/test';
 import fc from 'fast-check';
 
 const SimplePreUpgradeArb = PreUpgradeMethodArb({
@@ -92,7 +92,7 @@ function generateGetPreUpgradeExecutedCanisterMethod(): QueryMethod {
             [
                 {
                     name: `pre upgrade was not called after first deploy`,
-                    test: async () => {
+                    test: async (): Promise<AzleResult> => {
                         const actor = getActor(__dirname);
                         const result = await actor.getPreUpgradeExecuted();
 
@@ -103,7 +103,7 @@ function generateGetPreUpgradeExecutedCanisterMethod(): QueryMethod {
             [
                 {
                     name: `pre upgrade was called after second deploy`,
-                    test: async () => {
+                    test: async (): Promise<AzleResult> => {
                         const actor = getActor(__dirname);
                         const result = await actor.getPreUpgradeExecuted();
 
diff --git a/property_tests/tests/canister_methods/query/test/generate_tests.ts b/property_tests/tests/canister_methods/query/test/generate_tests.ts
index e621c8cb7d..3b11b5427c 100644
--- a/property_tests/tests/canister_methods/query/test/generate_tests.ts
+++ b/property_tests/tests/canister_methods/query/test/generate_tests.ts
@@ -2,7 +2,7 @@ import { getActor, Named } from 'azle/property_tests';
 import { CandidReturnType } from 'azle/property_tests/arbitraries/candid/candid_return_type_arb';
 import { CandidValueAndMeta } from 'azle/property_tests/arbitraries/candid/candid_value_and_meta_arb';
 import { CorrespondingJSType } from 'azle/property_tests/arbitraries/candid/corresponding_js_type';
-import { Test, testEquality } from 'azle/property_tests/test';
+import { AzleResult, Test, testEquality } from 'azle/property_tests/test';
 
 export function generateTests(
     functionName: string,
@@ -18,7 +18,7 @@ export function generateTests(
         [
             {
                 name: `query method "${functionName}"`,
-                test: async () => {
+                test: async (): Promise<AzleResult> => {
                     const actor = getActor(__dirname);
                     const result = await actor[functionName](...paramValues);
                     return testEquality(result, expectedResult);
diff --git a/property_tests/tests/canister_methods/update/test/generate_tests.ts b/property_tests/tests/canister_methods/update/test/generate_tests.ts
index 4760f033de..b922deb88a 100644
--- a/property_tests/tests/canister_methods/update/test/generate_tests.ts
+++ b/property_tests/tests/canister_methods/update/test/generate_tests.ts
@@ -2,7 +2,7 @@ import { getActor, Named } from 'azle/property_tests';
 import { CandidReturnType } from 'azle/property_tests/arbitraries/candid/candid_return_type_arb';
 import { CandidValueAndMeta } from 'azle/property_tests/arbitraries/candid/candid_value_and_meta_arb';
 import { CorrespondingJSType } from 'azle/property_tests/arbitraries/candid/corresponding_js_type';
-import { Test, testEquality } from 'azle/property_tests/test';
+import { AzleResult, Test, testEquality } from 'azle/property_tests/test';
 
 export function generateTests(
     functionName: string,
@@ -18,7 +18,7 @@ export function generateTests(
         [
             {
                 name: `update method "${functionName}"`,
-                test: async () => {
+                test: async (): Promise<AzleResult> => {
                     const actor = getActor(__dirname);
                     const result = await actor[functionName](...paramValues);
 
diff --git a/property_tests/tests/float32/test/generate_tests.ts b/property_tests/tests/float32/test/generate_tests.ts
index 5cff853dd5..44bbc97595 100644
--- a/property_tests/tests/float32/test/generate_tests.ts
+++ b/property_tests/tests/float32/test/generate_tests.ts
@@ -1,6 +1,6 @@
 import { getActor, Named } from 'azle/property_tests';
 import { CandidValueAndMeta } from 'azle/property_tests/arbitraries/candid/candid_value_and_meta_arb';
-import { Test, testEquality } from 'azle/property_tests/test';
+import { AzleResult, Test, testEquality } from 'azle/property_tests/test';
 
 export function generateTests(
     functionName: string,
@@ -18,7 +18,7 @@ export function generateTests(
         [
             {
                 name: `float32 ${functionName}`,
-                test: async () => {
+                test: async (): Promise<AzleResult> => {
                     const actor = getActor(__dirname);
 
                     const result = await actor[functionName](...paramValues);
diff --git a/property_tests/tests/float64/test/generate_tests.ts b/property_tests/tests/float64/test/generate_tests.ts
index c66aa80f29..cd5d42f3fe 100644
--- a/property_tests/tests/float64/test/generate_tests.ts
+++ b/property_tests/tests/float64/test/generate_tests.ts
@@ -1,6 +1,6 @@
 import { getActor, Named } from 'azle/property_tests';
 import { CandidValueAndMeta } from 'azle/property_tests/arbitraries/candid/candid_value_and_meta_arb';
-import { Test, testEquality } from 'azle/property_tests/test';
+import { AzleResult, Test, testEquality } from 'azle/property_tests/test';
 
 export function generateTests(
     functionName: string,
@@ -22,7 +22,7 @@ export function generateTests(
         [
             {
                 name: `float64 ${functionName}`,
-                test: async () => {
+                test: async (): Promise<AzleResult> => {
                     const actor = getActor(__dirname);
 
                     const result = await actor[functionName](...paramValues);
diff --git a/property_tests/tests/func/test/generate_tests.ts b/property_tests/tests/func/test/generate_tests.ts
index 15c72856fc..76a9739ccb 100644
--- a/property_tests/tests/func/test/generate_tests.ts
+++ b/property_tests/tests/func/test/generate_tests.ts
@@ -1,7 +1,7 @@
 import { getActor, Named } from 'azle/property_tests';
 import { CandidValueAndMeta } from 'azle/property_tests/arbitraries/candid/candid_value_and_meta_arb';
 import { Func } from 'azle/property_tests/arbitraries/candid/reference/func_arb';
-import { Test, testEquality } from 'azle/property_tests/test';
+import { AzleResult, Test, testEquality } from 'azle/property_tests/test';
 
 export function generateTests(
     functionName: string,
@@ -12,7 +12,7 @@ export function generateTests(
         [
             {
                 name: `func ${functionName}`,
-                test: async () => {
+                test: async (): Promise<AzleResult> => {
                     const actor = getActor(__dirname);
 
                     const result = await actor[functionName](
diff --git a/property_tests/tests/int/test/generate_tests.ts b/property_tests/tests/int/test/generate_tests.ts
index 9aba610ecb..4e58696822 100644
--- a/property_tests/tests/int/test/generate_tests.ts
+++ b/property_tests/tests/int/test/generate_tests.ts
@@ -1,6 +1,6 @@
 import { getActor, Named } from 'azle/property_tests';
 import { CandidValueAndMeta } from 'azle/property_tests/arbitraries/candid/candid_value_and_meta_arb';
-import { Test, testEquality } from 'azle/property_tests/test';
+import { AzleResult, Test, testEquality } from 'azle/property_tests/test';
 
 export function generateTests(
     functionName: string,
@@ -19,7 +19,7 @@ export function generateTests(
         [
             {
                 name: `int ${functionName}`,
-                test: async () => {
+                test: async (): Promise<AzleResult> => {
                     const actor = getActor(__dirname);
 
                     const result = await actor[functionName](...paramValues);
diff --git a/property_tests/tests/int16/test/generate_tests.ts b/property_tests/tests/int16/test/generate_tests.ts
index 234aa8fe58..a541579499 100644
--- a/property_tests/tests/int16/test/generate_tests.ts
+++ b/property_tests/tests/int16/test/generate_tests.ts
@@ -1,6 +1,6 @@
 import { getActor, Named } from 'azle/property_tests';
 import { CandidValueAndMeta } from 'azle/property_tests/arbitraries/candid/candid_value_and_meta_arb';
-import { Test, testEquality } from 'azle/property_tests/test';
+import { AzleResult, Test, testEquality } from 'azle/property_tests/test';
 
 export function generateTests(
     functionName: string,
@@ -22,7 +22,7 @@ export function generateTests(
         [
             {
                 name: `int16 ${functionName}`,
-                test: async () => {
+                test: async (): Promise<AzleResult> => {
                     const actor = getActor(__dirname);
 
                     const result = await actor[functionName](...paramValues);
diff --git a/property_tests/tests/int32/test/generate_tests.ts b/property_tests/tests/int32/test/generate_tests.ts
index 80810804a1..7e273b9729 100644
--- a/property_tests/tests/int32/test/generate_tests.ts
+++ b/property_tests/tests/int32/test/generate_tests.ts
@@ -1,6 +1,6 @@
 import { getActor, Named } from 'azle/property_tests';
 import { CandidValueAndMeta } from 'azle/property_tests/arbitraries/candid/candid_value_and_meta_arb';
-import { Test, testEquality } from 'azle/property_tests/test';
+import { AzleResult, Test, testEquality } from 'azle/property_tests/test';
 
 export function generateTests(
     functionName: string,
@@ -22,7 +22,7 @@ export function generateTests(
         [
             {
                 name: `int32 ${functionName}`,
-                test: async () => {
+                test: async (): Promise<AzleResult> => {
                     const actor = getActor(__dirname);
 
                     const result = await actor[functionName](...paramValues);
diff --git a/property_tests/tests/int64/test/generate_tests.ts b/property_tests/tests/int64/test/generate_tests.ts
index 2a675e694f..636992ed67 100644
--- a/property_tests/tests/int64/test/generate_tests.ts
+++ b/property_tests/tests/int64/test/generate_tests.ts
@@ -1,6 +1,6 @@
 import { getActor, Named } from 'azle/property_tests';
 import { CandidValueAndMeta } from 'azle/property_tests/arbitraries/candid/candid_value_and_meta_arb';
-import { Test, testEquality } from 'azle/property_tests/test';
+import { AzleResult, Test, testEquality } from 'azle/property_tests/test';
 
 export function generateTests(
     functionName: string,
@@ -21,7 +21,7 @@ export function generateTests(
         [
             {
                 name: `int64 ${functionName}`,
-                test: async () => {
+                test: async (): Promise<AzleResult> => {
                     const actor = getActor(__dirname);
 
                     const result = await actor[functionName](...paramValues);
diff --git a/property_tests/tests/int8/test/generate_tests.ts b/property_tests/tests/int8/test/generate_tests.ts
index 51a6cd2727..947d939c1d 100644
--- a/property_tests/tests/int8/test/generate_tests.ts
+++ b/property_tests/tests/int8/test/generate_tests.ts
@@ -1,6 +1,6 @@
 import { getActor, Named } from 'azle/property_tests';
 import { CandidValueAndMeta } from 'azle/property_tests/arbitraries/candid/candid_value_and_meta_arb';
-import { Test, testEquality } from 'azle/property_tests/test';
+import { AzleResult, Test, testEquality } from 'azle/property_tests/test';
 
 export function generateTests(
     functionName: string,
@@ -21,7 +21,7 @@ export function generateTests(
         [
             {
                 name: `test ${functionName}`,
-                test: async () => {
+                test: async (): Promise<AzleResult> => {
                     const actor = getActor(__dirname);
 
                     const result = await actor[functionName](...paramValues);
diff --git a/property_tests/tests/nat/test/generate_tests.ts b/property_tests/tests/nat/test/generate_tests.ts
index a11183c099..7cd446f07d 100644
--- a/property_tests/tests/nat/test/generate_tests.ts
+++ b/property_tests/tests/nat/test/generate_tests.ts
@@ -1,6 +1,6 @@
 import { getActor, Named } from 'azle/property_tests';
 import { CandidValueAndMeta } from 'azle/property_tests/arbitraries/candid/candid_value_and_meta_arb';
-import { Test, testEquality } from 'azle/property_tests/test';
+import { AzleResult, Test, testEquality } from 'azle/property_tests/test';
 
 export function generateTests(
     functionName: string,
@@ -19,7 +19,7 @@ export function generateTests(
         [
             {
                 name: `nat ${functionName}`,
-                test: async () => {
+                test: async (): Promise<AzleResult> => {
                     const actor = getActor(__dirname);
 
                     const result = await actor[functionName](...paramValues);
diff --git a/property_tests/tests/nat16/test/generate_tests.ts b/property_tests/tests/nat16/test/generate_tests.ts
index 277b523ac9..712cfd11df 100644
--- a/property_tests/tests/nat16/test/generate_tests.ts
+++ b/property_tests/tests/nat16/test/generate_tests.ts
@@ -1,6 +1,6 @@
 import { getActor, Named } from 'azle/property_tests';
 import { CandidValueAndMeta } from 'azle/property_tests/arbitraries/candid/candid_value_and_meta_arb';
-import { Test, testEquality } from 'azle/property_tests/test';
+import { AzleResult, Test, testEquality } from 'azle/property_tests/test';
 
 export function generateTests(
     functionName: string,
@@ -22,7 +22,7 @@ export function generateTests(
         [
             {
                 name: `nat16 ${functionName}`,
-                test: async () => {
+                test: async (): Promise<AzleResult> => {
                     const actor = getActor(__dirname);
 
                     const result = await actor[functionName](...paramValues);
diff --git a/property_tests/tests/nat32/test/generate_tests.ts b/property_tests/tests/nat32/test/generate_tests.ts
index 31af6ffae4..9b67e1291b 100644
--- a/property_tests/tests/nat32/test/generate_tests.ts
+++ b/property_tests/tests/nat32/test/generate_tests.ts
@@ -1,6 +1,6 @@
 import { getActor, Named } from 'azle/property_tests';
 import { CandidValueAndMeta } from 'azle/property_tests/arbitraries/candid/candid_value_and_meta_arb';
-import { Test, testEquality } from 'azle/property_tests/test';
+import { AzleResult, Test, testEquality } from 'azle/property_tests/test';
 
 export function generateTests(
     functionName: string,
@@ -22,7 +22,7 @@ export function generateTests(
         [
             {
                 name: `nat32 ${functionName}`,
-                test: async () => {
+                test: async (): Promise<AzleResult> => {
                     const actor = getActor(__dirname);
 
                     const result = await actor[functionName](...paramValues);
diff --git a/property_tests/tests/nat64/test/generate_tests.ts b/property_tests/tests/nat64/test/generate_tests.ts
index afd523ad67..1bf97bf853 100644
--- a/property_tests/tests/nat64/test/generate_tests.ts
+++ b/property_tests/tests/nat64/test/generate_tests.ts
@@ -1,6 +1,6 @@
 import { getActor, Named } from 'azle/property_tests';
 import { CandidValueAndMeta } from 'azle/property_tests/arbitraries/candid/candid_value_and_meta_arb';
-import { Test, testEquality } from 'azle/property_tests/test';
+import { AzleResult, Test, testEquality } from 'azle/property_tests/test';
 
 export function generateTests(
     functionName: string,
@@ -21,7 +21,7 @@ export function generateTests(
         [
             {
                 name: `nat64 ${functionName}`,
-                test: async () => {
+                test: async (): Promise<AzleResult> => {
                     const actor = getActor(__dirname);
 
                     const result = await actor[functionName](...paramValues);
diff --git a/property_tests/tests/nat8/test/generate_tests.ts b/property_tests/tests/nat8/test/generate_tests.ts
index cdba09a15f..10e8bc18a4 100644
--- a/property_tests/tests/nat8/test/generate_tests.ts
+++ b/property_tests/tests/nat8/test/generate_tests.ts
@@ -1,6 +1,6 @@
 import { getActor, Named } from 'azle/property_tests';
 import { CandidValueAndMeta } from 'azle/property_tests/arbitraries/candid/candid_value_and_meta_arb';
-import { Test, testEquality } from 'azle/property_tests/test';
+import { AzleResult, Test, testEquality } from 'azle/property_tests/test';
 
 export function generateTests(
     functionName: string,
@@ -22,7 +22,7 @@ export function generateTests(
         [
             {
                 name: `nat8 ${functionName}`,
-                test: async () => {
+                test: async (): Promise<AzleResult> => {
                     const actor = getActor(__dirname);
 
                     const result = await actor[functionName](...paramValues);
diff --git a/property_tests/tests/null/test/generate_tests.ts b/property_tests/tests/null/test/generate_tests.ts
index 9b173f2c4b..ab971a20d4 100644
--- a/property_tests/tests/null/test/generate_tests.ts
+++ b/property_tests/tests/null/test/generate_tests.ts
@@ -1,6 +1,6 @@
 import { getActor, Named } from 'azle/property_tests';
 import { CandidValueAndMeta } from 'azle/property_tests/arbitraries/candid/candid_value_and_meta_arb';
-import { Test, testEquality } from 'azle/property_tests/test';
+import { AzleResult, Test, testEquality } from 'azle/property_tests/test';
 
 export function generateTests(
     functionName: string,
@@ -11,7 +11,7 @@ export function generateTests(
         [
             {
                 name: `test ${functionName}`,
-                test: async () => {
+                test: async (): Promise<AzleResult> => {
                     const actor = getActor(__dirname);
 
                     const result = await actor[functionName](
diff --git a/property_tests/tests/opt/test/generate_tests.ts b/property_tests/tests/opt/test/generate_tests.ts
index 97c125f15c..1c6ce71905 100644
--- a/property_tests/tests/opt/test/generate_tests.ts
+++ b/property_tests/tests/opt/test/generate_tests.ts
@@ -1,7 +1,7 @@
 import { getActor, Named } from 'azle/property_tests';
 import { CandidValueAndMeta } from 'azle/property_tests/arbitraries/candid/candid_value_and_meta_arb';
 import { Opt } from 'azle/property_tests/arbitraries/candid/constructed/opt_arb';
-import { Test, testEquality } from 'azle/property_tests/test';
+import { AzleResult, Test, testEquality } from 'azle/property_tests/test';
 
 export function generateTests(
     functionName: string,
@@ -14,7 +14,7 @@ export function generateTests(
         [
             {
                 name: `opt ${functionName}`,
-                test: async () => {
+                test: async (): Promise<AzleResult> => {
                     const actor = getActor(__dirname);
 
                     const params = namedParamOpts.map(
diff --git a/property_tests/tests/principal/test/generate_tests.ts b/property_tests/tests/principal/test/generate_tests.ts
index 01c755044e..05f59dc620 100644
--- a/property_tests/tests/principal/test/generate_tests.ts
+++ b/property_tests/tests/principal/test/generate_tests.ts
@@ -1,7 +1,7 @@
 import { Principal } from '@dfinity/principal';
 import { getActor, Named } from 'azle/property_tests';
 import { CandidValueAndMeta } from 'azle/property_tests/arbitraries/candid/candid_value_and_meta_arb';
-import { Test, testEquality } from 'azle/property_tests/test';
+import { AzleResult, Test, testEquality } from 'azle/property_tests/test';
 
 export function generateTests(
     functionName: string,
@@ -17,7 +17,7 @@ export function generateTests(
         [
             {
                 name: `principal ${functionName}`,
-                test: async () => {
+                test: async (): Promise<AzleResult> => {
                     const actor = getActor(__dirname);
                     const result = await actor[functionName](
                         ...namedParamPrincipals.map(
diff --git a/property_tests/tests/record/test/generate_tests.ts b/property_tests/tests/record/test/generate_tests.ts
index 6439dd5e33..e23fd20329 100644
--- a/property_tests/tests/record/test/generate_tests.ts
+++ b/property_tests/tests/record/test/generate_tests.ts
@@ -1,7 +1,7 @@
 import { getActor, Named } from 'azle/property_tests';
 import { CandidValueAndMeta } from 'azle/property_tests/arbitraries/candid/candid_value_and_meta_arb';
 import { Record } from 'azle/property_tests/arbitraries/candid/constructed/record_arb';
-import { Test, testEquality } from 'azle/property_tests/test';
+import { AzleResult, Test, testEquality } from 'azle/property_tests/test';
 
 export function generateTests(
     functionName: string,
@@ -12,7 +12,7 @@ export function generateTests(
         [
             {
                 name: `record ${functionName}`,
-                test: async () => {
+                test: async (): Promise<AzleResult> => {
                     const actor = getActor(__dirname);
 
                     const result = await actor[functionName](
diff --git a/property_tests/tests/recursive/test/generate_tests.ts b/property_tests/tests/recursive/test/generate_tests.ts
index 281d8962db..d6459ffb9e 100644
--- a/property_tests/tests/recursive/test/generate_tests.ts
+++ b/property_tests/tests/recursive/test/generate_tests.ts
@@ -1,7 +1,7 @@
 import { getActor, Named } from 'azle/property_tests';
 import { CandidValueAndMeta } from 'azle/property_tests/arbitraries/candid/candid_value_and_meta_arb';
 import { Recursive } from 'azle/property_tests/arbitraries/candid/recursive';
-import { Test, testEquality } from 'azle/property_tests/test';
+import { AzleResult, Test, testEquality } from 'azle/property_tests/test';
 
 export function generateTests(
     functionName: string,
@@ -12,7 +12,7 @@ export function generateTests(
         [
             {
                 name: `recursive ${functionName}`,
-                test: async () => {
+                test: async (): Promise<AzleResult> => {
                     const actor = getActor(__dirname);
 
                     const params = namedParamRecursive.map(
diff --git a/property_tests/tests/service/test/generate_tests.ts b/property_tests/tests/service/test/generate_tests.ts
index db6571483b..0f28d07c9c 100644
--- a/property_tests/tests/service/test/generate_tests.ts
+++ b/property_tests/tests/service/test/generate_tests.ts
@@ -1,7 +1,7 @@
 import { Principal } from '@dfinity/principal';
 import { Named } from 'azle/property_tests';
 import { CandidValueAndMeta } from 'azle/property_tests/arbitraries/candid/candid_value_and_meta_arb';
-import { Test, testEquality } from 'azle/property_tests/test';
+import { AzleResult, Test, testEquality } from 'azle/property_tests/test';
 import { execSync } from 'child_process';
 
 export function generateTests(
@@ -13,7 +13,7 @@ export function generateTests(
         [
             {
                 name: `service ${functionName}`,
-                test: async () => {
+                test: async (): Promise<AzleResult> => {
                     // Using execSync because the JS Agent has a bug expecting services
                     // to be ordered by hash or something.
                     // See https://forum.dfinity.org/t/topic/20885/14
diff --git a/property_tests/tests/stable_b_tree_map/test/contains_key.ts b/property_tests/tests/stable_b_tree_map/test/contains_key.ts
index da96ce78aa..74dddc6234 100644
--- a/property_tests/tests/stable_b_tree_map/test/contains_key.ts
+++ b/property_tests/tests/stable_b_tree_map/test/contains_key.ts
@@ -2,10 +2,12 @@ import { deepEqual, getActor } from 'azle/property_tests';
 import { QueryMethod } from 'azle/property_tests/arbitraries/canister_methods/query_method_arb';
 import { StableBTreeMap } from 'azle/property_tests/arbitraries/stable_b_tree_map_arb';
 import { UniqueIdentifierArb } from 'azle/property_tests/arbitraries/unique_identifier_arb';
-import { Test } from 'azle/property_tests/test';
+import { AzleResult, Test } from 'azle/property_tests/test';
 import fc from 'fast-check';
 
-export function ContainsKeyTestArb(stableBTreeMap: StableBTreeMap) {
+export function ContainsKeyTestArb(
+    stableBTreeMap: StableBTreeMap
+): fc.Arbitrary<QueryMethod> {
     return fc
         .tuple(UniqueIdentifierArb('canisterProperties'))
         .map(([functionName]): QueryMethod => {
@@ -51,7 +53,7 @@ function generateTests(
         [
             {
                 name: `containsKey after first deploy ${functionName}`,
-                test: async () => {
+                test: async (): Promise<AzleResult> => {
                     const actor = getActor(__dirname);
 
                     const result = await actor[functionName](
@@ -67,7 +69,7 @@ function generateTests(
         [
             {
                 name: `containsKey after second deploy ${functionName}`,
-                test: async () => {
+                test: async (): Promise<AzleResult> => {
                     const actor = getActor(__dirname);
 
                     const result = await actor[functionName](
@@ -83,7 +85,7 @@ function generateTests(
         [
             {
                 name: `containsKey after third deploy ${functionName}`,
-                test: async () => {
+                test: async (): Promise<AzleResult> => {
                     const actor = getActor(__dirname);
 
                     const result = await actor[functionName](
diff --git a/property_tests/tests/stable_b_tree_map/test/get.ts b/property_tests/tests/stable_b_tree_map/test/get.ts
index dab7465ba8..a2e79c7124 100644
--- a/property_tests/tests/stable_b_tree_map/test/get.ts
+++ b/property_tests/tests/stable_b_tree_map/test/get.ts
@@ -2,10 +2,12 @@ import { deepEqual, getActor } from 'azle/property_tests';
 import { QueryMethod } from 'azle/property_tests/arbitraries/canister_methods/query_method_arb';
 import { StableBTreeMap } from 'azle/property_tests/arbitraries/stable_b_tree_map_arb';
 import { UniqueIdentifierArb } from 'azle/property_tests/arbitraries/unique_identifier_arb';
-import { Test } from 'azle/property_tests/test';
+import { AzleResult, Test } from 'azle/property_tests/test';
 import fc from 'fast-check';
 
-export function GetTestArb(stableBTreeMap: StableBTreeMap) {
+export function GetTestArb(
+    stableBTreeMap: StableBTreeMap
+): fc.Arbitrary<QueryMethod> {
     return fc
         .tuple(UniqueIdentifierArb('canisterProperties'))
         .map(([functionName]): QueryMethod => {
@@ -54,7 +56,7 @@ function generateTests(
         [
             {
                 name: `get after first deploy ${functionName}`,
-                test: async () => {
+                test: async (): Promise<AzleResult> => {
                     const actor = getActor(__dirname);
 
                     const result = await actor[functionName](
@@ -70,7 +72,7 @@ function generateTests(
         [
             {
                 name: `get after second deploy ${functionName}`,
-                test: async () => {
+                test: async (): Promise<AzleResult> => {
                     const actor = getActor(__dirname);
 
                     const result = await actor[functionName](
@@ -86,7 +88,7 @@ function generateTests(
         [
             {
                 name: `get after third deploy ${functionName}`,
-                test: async () => {
+                test: async (): Promise<AzleResult> => {
                     const actor = getActor(__dirname);
 
                     const result = await actor[functionName](
diff --git a/property_tests/tests/stable_b_tree_map/test/insert.ts b/property_tests/tests/stable_b_tree_map/test/insert.ts
index 5cc7c51523..b36a2a1639 100644
--- a/property_tests/tests/stable_b_tree_map/test/insert.ts
+++ b/property_tests/tests/stable_b_tree_map/test/insert.ts
@@ -2,10 +2,12 @@ import { deepEqual, getActor } from 'azle/property_tests';
 import { QueryMethod } from 'azle/property_tests/arbitraries/canister_methods/query_method_arb';
 import { StableBTreeMap } from 'azle/property_tests/arbitraries/stable_b_tree_map_arb';
 import { UniqueIdentifierArb } from 'azle/property_tests/arbitraries/unique_identifier_arb';
-import { Test } from 'azle/property_tests/test';
+import { AzleResult, Test } from 'azle/property_tests/test';
 import fc from 'fast-check';
 
-export function InsertTestArb(stableBTreeMap: StableBTreeMap) {
+export function InsertTestArb(
+    stableBTreeMap: StableBTreeMap
+): fc.Arbitrary<QueryMethod> {
     return fc
         .tuple(UniqueIdentifierArb('canisterProperties'))
         .map(([functionName]): QueryMethod => {
@@ -55,7 +57,7 @@ function generateTests(
         [
             {
                 name: `insert after first deploy ${functionName}`,
-                test: async () => {
+                test: async (): Promise<AzleResult> => {
                     const actor = getActor(__dirname);
 
                     const result = await actor[functionName](
diff --git a/property_tests/tests/stable_b_tree_map/test/is_empty.ts b/property_tests/tests/stable_b_tree_map/test/is_empty.ts
index d793cc32e4..5cfad8dda6 100644
--- a/property_tests/tests/stable_b_tree_map/test/is_empty.ts
+++ b/property_tests/tests/stable_b_tree_map/test/is_empty.ts
@@ -2,10 +2,12 @@ import { deepEqual, getActor } from 'azle/property_tests';
 import { QueryMethod } from 'azle/property_tests/arbitraries/canister_methods/query_method_arb';
 import { StableBTreeMap } from 'azle/property_tests/arbitraries/stable_b_tree_map_arb';
 import { UniqueIdentifierArb } from 'azle/property_tests/arbitraries/unique_identifier_arb';
-import { Test } from 'azle/property_tests/test';
+import { AzleResult, Test } from 'azle/property_tests/test';
 import fc from 'fast-check';
 
-export function IsEmptyTestArb(stableBTreeMap: StableBTreeMap) {
+export function IsEmptyTestArb(
+    stableBTreeMap: StableBTreeMap
+): fc.Arbitrary<QueryMethod> {
     return fc
         .tuple(UniqueIdentifierArb('canisterProperties'))
         .map(([functionName]): QueryMethod => {
@@ -41,7 +43,7 @@ function generateTests(functionName: string): Test[][] {
         [
             {
                 name: `isEmpty after first deploy ${functionName}`,
-                test: async () => {
+                test: async (): Promise<AzleResult> => {
                     const actor = getActor(__dirname);
 
                     const result = await actor[functionName]();
@@ -55,7 +57,7 @@ function generateTests(functionName: string): Test[][] {
         [
             {
                 name: `isEmpty after second deploy ${functionName}`,
-                test: async () => {
+                test: async (): Promise<AzleResult> => {
                     const actor = getActor(__dirname);
 
                     const result = await actor[functionName]();
@@ -69,7 +71,7 @@ function generateTests(functionName: string): Test[][] {
         [
             {
                 name: `isEmpty after third deploy ${functionName}`,
-                test: async () => {
+                test: async (): Promise<AzleResult> => {
                     const actor = getActor(__dirname);
 
                     const result = await actor[functionName]();
diff --git a/property_tests/tests/stable_b_tree_map/test/items.ts b/property_tests/tests/stable_b_tree_map/test/items.ts
index 5131c949c0..d05a6cb122 100644
--- a/property_tests/tests/stable_b_tree_map/test/items.ts
+++ b/property_tests/tests/stable_b_tree_map/test/items.ts
@@ -2,10 +2,12 @@ import { deepEqual, getActor } from 'azle/property_tests';
 import { QueryMethod } from 'azle/property_tests/arbitraries/canister_methods/query_method_arb';
 import { StableBTreeMap } from 'azle/property_tests/arbitraries/stable_b_tree_map_arb';
 import { UniqueIdentifierArb } from 'azle/property_tests/arbitraries/unique_identifier_arb';
-import { Test } from 'azle/property_tests/test';
+import { AzleResult, Test } from 'azle/property_tests/test';
 import fc from 'fast-check';
 
-export function ItemsTestArb(stableBTreeMap: StableBTreeMap) {
+export function ItemsTestArb(
+    stableBTreeMap: StableBTreeMap
+): fc.Arbitrary<QueryMethod> {
     return fc
         .tuple(UniqueIdentifierArb('canisterProperties'))
         .map(([functionName]): QueryMethod => {
@@ -51,7 +53,7 @@ function generateTests(
         [
             {
                 name: `items after first deploy ${functionName}`,
-                test: async () => {
+                test: async (): Promise<AzleResult> => {
                     const actor = getActor(__dirname);
 
                     const result = await actor[functionName]();
@@ -70,7 +72,7 @@ function generateTests(
         [
             {
                 name: `items after second deploy ${functionName}`,
-                test: async () => {
+                test: async (): Promise<AzleResult> => {
                     const actor = getActor(__dirname);
 
                     const result = await actor[functionName]();
@@ -89,7 +91,7 @@ function generateTests(
         [
             {
                 name: `items after third deploy ${functionName}`,
-                test: async () => {
+                test: async (): Promise<AzleResult> => {
                     const actor = getActor(__dirname);
 
                     const result = await actor[functionName]();
diff --git a/property_tests/tests/stable_b_tree_map/test/keys.ts b/property_tests/tests/stable_b_tree_map/test/keys.ts
index f26e5802f4..8777f4f1f2 100644
--- a/property_tests/tests/stable_b_tree_map/test/keys.ts
+++ b/property_tests/tests/stable_b_tree_map/test/keys.ts
@@ -2,12 +2,14 @@ import { deepEqual, getActor } from 'azle/property_tests';
 import { QueryMethod } from 'azle/property_tests/arbitraries/canister_methods/query_method_arb';
 import { StableBTreeMap } from 'azle/property_tests/arbitraries/stable_b_tree_map_arb';
 import { UniqueIdentifierArb } from 'azle/property_tests/arbitraries/unique_identifier_arb';
-import { Test } from 'azle/property_tests/test';
+import { AzleResult, Test } from 'azle/property_tests/test';
 import fc from 'fast-check';
 
 import { getArrayForCandidType, getArrayStringForCandidType } from './utils';
 
-export function KeysTestArb(stableBTreeMap: StableBTreeMap) {
+export function KeysTestArb(
+    stableBTreeMap: StableBTreeMap
+): fc.Arbitrary<QueryMethod> {
     return fc
         .tuple(UniqueIdentifierArb('canisterProperties'))
         .map(([functionName]): QueryMethod => {
@@ -55,7 +57,7 @@ function generateTests(
         [
             {
                 name: `keys after first deploy ${functionName}`,
-                test: async () => {
+                test: async (): Promise<AzleResult> => {
                     const actor = getActor(__dirname);
 
                     const result = await actor[functionName]();
@@ -76,7 +78,7 @@ function generateTests(
         [
             {
                 name: `keys after second deploy ${functionName}`,
-                test: async () => {
+                test: async (): Promise<AzleResult> => {
                     const actor = getActor(__dirname);
 
                     const result = await actor[functionName]();
@@ -97,7 +99,7 @@ function generateTests(
         [
             {
                 name: `keys after third deploy ${functionName}`,
-                test: async () => {
+                test: async (): Promise<AzleResult> => {
                     const actor = getActor(__dirname);
 
                     const result = await actor[functionName]();
diff --git a/property_tests/tests/stable_b_tree_map/test/len.ts b/property_tests/tests/stable_b_tree_map/test/len.ts
index 9bc86901ba..5b69ee7bd8 100644
--- a/property_tests/tests/stable_b_tree_map/test/len.ts
+++ b/property_tests/tests/stable_b_tree_map/test/len.ts
@@ -2,10 +2,12 @@ import { deepEqual, getActor } from 'azle/property_tests';
 import { QueryMethod } from 'azle/property_tests/arbitraries/canister_methods/query_method_arb';
 import { StableBTreeMap } from 'azle/property_tests/arbitraries/stable_b_tree_map_arb';
 import { UniqueIdentifierArb } from 'azle/property_tests/arbitraries/unique_identifier_arb';
-import { Test } from 'azle/property_tests/test';
+import { AzleResult, Test } from 'azle/property_tests/test';
 import fc from 'fast-check';
 
-export function LenTestArb(stableBTreeMap: StableBTreeMap) {
+export function LenTestArb(
+    stableBTreeMap: StableBTreeMap
+): fc.Arbitrary<QueryMethod> {
     return fc
         .tuple(UniqueIdentifierArb('canisterProperties'))
         .map(([functionName]): QueryMethod => {
@@ -42,7 +44,7 @@ function generateTests(functionName: string): Test[][] {
         [
             {
                 name: `len after first deploy ${functionName}`,
-                test: async () => {
+                test: async (): Promise<AzleResult> => {
                     const actor = getActor(__dirname);
 
                     const result = await actor[functionName]();
@@ -56,7 +58,7 @@ function generateTests(functionName: string): Test[][] {
         [
             {
                 name: `len after second deploy ${functionName}`,
-                test: async () => {
+                test: async (): Promise<AzleResult> => {
                     const actor = getActor(__dirname);
 
                     const result = await actor[functionName]();
@@ -70,7 +72,7 @@ function generateTests(functionName: string): Test[][] {
         [
             {
                 name: `len after third deploy ${functionName}`,
-                test: async () => {
+                test: async (): Promise<AzleResult> => {
                     const actor = getActor(__dirname);
 
                     const result = await actor[functionName]();
diff --git a/property_tests/tests/stable_b_tree_map/test/remove.ts b/property_tests/tests/stable_b_tree_map/test/remove.ts
index f94b6b0734..2dd80a385c 100644
--- a/property_tests/tests/stable_b_tree_map/test/remove.ts
+++ b/property_tests/tests/stable_b_tree_map/test/remove.ts
@@ -2,10 +2,12 @@ import { deepEqual, getActor } from 'azle/property_tests';
 import { QueryMethod } from 'azle/property_tests/arbitraries/canister_methods/query_method_arb';
 import { StableBTreeMap } from 'azle/property_tests/arbitraries/stable_b_tree_map_arb';
 import { UniqueIdentifierArb } from 'azle/property_tests/arbitraries/unique_identifier_arb';
-import { Test } from 'azle/property_tests/test';
+import { AzleResult, Test } from 'azle/property_tests/test';
 import fc from 'fast-check';
 
-export function RemoveTestArb(stableBTreeMap: StableBTreeMap) {
+export function RemoveTestArb(
+    stableBTreeMap: StableBTreeMap
+): fc.Arbitrary<QueryMethod> {
     return fc
         .tuple(UniqueIdentifierArb('canisterProperties'))
         .map(([functionName]): QueryMethod => {
@@ -55,7 +57,7 @@ function generateTests(
         [
             {
                 name: `remove after second deploy ${functionName}`,
-                test: async () => {
+                test: async (): Promise<AzleResult> => {
                     const actor = getActor(__dirname);
 
                     const result = await actor[functionName](
diff --git a/property_tests/tests/stable_b_tree_map/test/values.ts b/property_tests/tests/stable_b_tree_map/test/values.ts
index 2ebe6bab4c..bf0d75de62 100644
--- a/property_tests/tests/stable_b_tree_map/test/values.ts
+++ b/property_tests/tests/stable_b_tree_map/test/values.ts
@@ -2,12 +2,14 @@ import { deepEqual, getActor } from 'azle/property_tests';
 import { QueryMethod } from 'azle/property_tests/arbitraries/canister_methods/query_method_arb';
 import { StableBTreeMap } from 'azle/property_tests/arbitraries/stable_b_tree_map_arb';
 import { UniqueIdentifierArb } from 'azle/property_tests/arbitraries/unique_identifier_arb';
-import { Test } from 'azle/property_tests/test';
+import { AzleResult, Test } from 'azle/property_tests/test';
 import fc from 'fast-check';
 
 import { getArrayForCandidType, getArrayStringForCandidType } from './utils';
 
-export function ValuesTestArb(stableBTreeMap: StableBTreeMap) {
+export function ValuesTestArb(
+    stableBTreeMap: StableBTreeMap
+): fc.Arbitrary<QueryMethod> {
     return fc
         .tuple(UniqueIdentifierArb('canisterProperties'))
         .map(([functionName]): QueryMethod => {
@@ -58,7 +60,7 @@ function generateTests(
         [
             {
                 name: `values after first deploy ${functionName}`,
-                test: async () => {
+                test: async (): Promise<AzleResult> => {
                     const actor = getActor(__dirname);
 
                     const result = await actor[functionName]();
@@ -79,7 +81,7 @@ function generateTests(
         [
             {
                 name: `values after second deploy ${functionName}`,
-                test: async () => {
+                test: async (): Promise<AzleResult> => {
                     const actor = getActor(__dirname);
 
                     const result = await actor[functionName]();
@@ -100,7 +102,7 @@ function generateTests(
         [
             {
                 name: `values after third deploy ${functionName}`,
-                test: async () => {
+                test: async (): Promise<AzleResult> => {
                     const actor = getActor(__dirname);
 
                     const result = await actor[functionName]();
diff --git a/property_tests/tests/text/test/generate_tests.ts b/property_tests/tests/text/test/generate_tests.ts
index ddc7df539e..370e30d251 100644
--- a/property_tests/tests/text/test/generate_tests.ts
+++ b/property_tests/tests/text/test/generate_tests.ts
@@ -1,6 +1,6 @@
 import { getActor, Named } from 'azle/property_tests';
 import { CandidValueAndMeta } from 'azle/property_tests/arbitraries/candid/candid_value_and_meta_arb';
-import { Test, testEquality } from 'azle/property_tests/test';
+import { AzleResult, Test, testEquality } from 'azle/property_tests/test';
 
 export function generateTests(
     functionName: string,
@@ -19,7 +19,7 @@ export function generateTests(
         [
             {
                 name: `text ${functionName}`,
-                test: async () => {
+                test: async (): Promise<AzleResult> => {
                     const actor = getActor(__dirname);
 
                     const result = await actor[functionName](...paramValues);
diff --git a/property_tests/tests/tuple/test/generate_tests.ts b/property_tests/tests/tuple/test/generate_tests.ts
index 871effb5e0..c35eedb756 100644
--- a/property_tests/tests/tuple/test/generate_tests.ts
+++ b/property_tests/tests/tuple/test/generate_tests.ts
@@ -4,7 +4,7 @@ import {
     ReturnTuple,
     Tuple
 } from 'azle/property_tests/arbitraries/candid/constructed/tuple_arb';
-import { Test, testEquality } from 'azle/property_tests/test';
+import { AzleResult, Test, testEquality } from 'azle/property_tests/test';
 
 export function generateTests(
     functionName: string,
@@ -17,7 +17,7 @@ export function generateTests(
         [
             {
                 name: `tuple ${functionName}`,
-                test: async () => {
+                test: async (): Promise<AzleResult> => {
                     const actor = getActor(__dirname);
 
                     const result = await actor[functionName](
diff --git a/property_tests/tests/variant/test/generate_tests.ts b/property_tests/tests/variant/test/generate_tests.ts
index 5cc03a2641..d9e46079d2 100644
--- a/property_tests/tests/variant/test/generate_tests.ts
+++ b/property_tests/tests/variant/test/generate_tests.ts
@@ -1,7 +1,7 @@
 import { getActor, Named } from 'azle/property_tests';
 import { CandidValueAndMeta } from 'azle/property_tests/arbitraries/candid/candid_value_and_meta_arb';
 import { Variant } from 'azle/property_tests/arbitraries/candid/constructed/variant_arb';
-import { Test, testEquality } from 'azle/property_tests/test';
+import { AzleResult, Test, testEquality } from 'azle/property_tests/test';
 
 export function generateTests(
     functionName: string,
@@ -14,7 +14,7 @@ export function generateTests(
         [
             {
                 name: `variant ${functionName}`,
-                test: async () => {
+                test: async (): Promise<AzleResult> => {
                     const actor = getActor(__dirname);
 
                     const result = await actor[functionName](
diff --git a/property_tests/tests/vec/test/generate_tests.ts b/property_tests/tests/vec/test/generate_tests.ts
index 0b357fe6ab..f668d981b1 100644
--- a/property_tests/tests/vec/test/generate_tests.ts
+++ b/property_tests/tests/vec/test/generate_tests.ts
@@ -1,6 +1,6 @@
 import { getActor, Named } from 'azle/property_tests';
 import { CandidValueAndMeta } from 'azle/property_tests/arbitraries/candid/candid_value_and_meta_arb';
-import { Test, testEquality } from 'azle/property_tests/test';
+import { AzleResult, Test, testEquality } from 'azle/property_tests/test';
 
 export function generateTests(
     functionName: string,
@@ -13,7 +13,7 @@ export function generateTests(
         [
             {
                 name: `vec ${functionName}`,
-                test: async () => {
+                test: async (): Promise<AzleResult> => {
                     const actor = getActor(__dirname);
 
                     const params = namedParamVecs.map(
diff --git a/property_tests/visitors/cli-string-visitor.ts b/property_tests/visitors/cli-string-visitor.ts
index 1ea78152c2..b8e9a5b3b2 100644
--- a/property_tests/visitors/cli-string-visitor.ts
+++ b/property_tests/visitors/cli-string-visitor.ts
@@ -8,7 +8,7 @@ export type VisitorData = { value: any };
  * as dfx deploy
  */
 export class CliStringVisitor extends IDL.Visitor<VisitorData, string> {
-    visitFloat(_t: IDL.FloatClass, data: VisitorData) {
+    visitFloat(_t: IDL.FloatClass, data: VisitorData): any {
         /**
          * If a float doesn't have a decimal it won't serialize properly, so
          * while 10 is a float it won't serialize unless it's 10.0
@@ -97,7 +97,7 @@ export class CliStringVisitor extends IDL.Visitor<VisitorData, string> {
     }
 }
 
-function escapeForBash(input: string) {
+function escapeForBash(input: string): string {
     return input
         .replace(/\\/g, '\\\\') // Escape backslashes
         .replace(/'/g, "'\\''") // Escape single quotes
diff --git a/scripts/add_metadata_to_dfx_json.js b/scripts/add_metadata_to_dfx_json.js
index d51c6333ce..c57db99d40 100644
--- a/scripts/add_metadata_to_dfx_json.js
+++ b/scripts/add_metadata_to_dfx_json.js
@@ -1,3 +1,4 @@
+/* eslint-disable @typescript-eslint/explicit-function-return-type */
 // eslint-disable-next-line @typescript-eslint/no-var-requires
 const fs = require('fs');
 // eslint-disable-next-line @typescript-eslint/no-var-requires
diff --git a/scripts/class_migration/clean_package.js b/scripts/class_migration/clean_package.js
index a668bd8dd2..36ef773b86 100644
--- a/scripts/class_migration/clean_package.js
+++ b/scripts/class_migration/clean_package.js
@@ -1,3 +1,4 @@
+/* eslint-disable @typescript-eslint/explicit-function-return-type */
 // eslint-disable-next-line @typescript-eslint/no-var-requires
 const fs = require('fs');
 // eslint-disable-next-line @typescript-eslint/no-var-requires
diff --git a/scripts/class_migration/copy_generated_candid_from_example.js b/scripts/class_migration/copy_generated_candid_from_example.js
index b940dea017..a33053aab8 100644
--- a/scripts/class_migration/copy_generated_candid_from_example.js
+++ b/scripts/class_migration/copy_generated_candid_from_example.js
@@ -1,3 +1,4 @@
+/* eslint-disable @typescript-eslint/explicit-function-return-type */
 // eslint-disable-next-line @typescript-eslint/no-var-requires
 const fs = require('fs');
 // eslint-disable-next-line @typescript-eslint/no-var-requires
diff --git a/scripts/class_migration/delete_tests_file.js b/scripts/class_migration/delete_tests_file.js
index ed553b2f99..5ff787b371 100644
--- a/scripts/class_migration/delete_tests_file.js
+++ b/scripts/class_migration/delete_tests_file.js
@@ -1,3 +1,4 @@
+/* eslint-disable @typescript-eslint/explicit-function-return-type */
 // eslint-disable-next-line @typescript-eslint/no-var-requires
 const fs = require('fs');
 // eslint-disable-next-line @typescript-eslint/no-var-requires
diff --git a/scripts/file_generator/index.ts b/scripts/file_generator/index.ts
index 754d19070b..92c21c846f 100644
--- a/scripts/file_generator/index.ts
+++ b/scripts/file_generator/index.ts
@@ -4,7 +4,10 @@ import { dirname } from 'path';
 export type Unit = 'B' | 'KiB' | 'MiB' | 'GiB';
 
 // Function to create a file of a specific size in bytes
-export async function generateFileOfSize(path: string, sizeInBytes: number) {
+export async function generateFileOfSize(
+    path: string,
+    sizeInBytes: number
+): Promise<void> {
     await ensureDirectoryExists(path);
     await ensureFileEmptyOrCreate(path);
     await fillFileWithRandomBytes(path, sizeInBytes);
@@ -25,15 +28,18 @@ export function toBytes(numBytes: number, unit: Unit): number {
     throw new Error('Invalid Unit. Must be B, KiB, MiB, or GiB');
 }
 
-async function ensureDirectoryExists(path: string) {
+async function ensureDirectoryExists(path: string): Promise<void> {
     await mkdir(dirname(path), { recursive: true });
 }
 
-async function ensureFileEmptyOrCreate(path: string) {
+async function ensureFileEmptyOrCreate(path: string): Promise<void> {
     await writeFile(path, Buffer.from([]));
 }
 
-async function fillFileWithRandomBytes(path: string, sizeInBytes: number) {
+async function fillFileWithRandomBytes(
+    path: string,
+    sizeInBytes: number
+): Promise<void> {
     const defaultChunkSize = 1024 * 1024; // 1 MiB. Size can be adjusted. By trial and error this gave good speeds and 1MB should be small enough for most machines running this to handle
     const totalChunks = Math.ceil(sizeInBytes / defaultChunkSize);
     for (let i = 0; i < totalChunks; i++) {
diff --git a/scripts/file_generator/main.ts b/scripts/file_generator/main.ts
index 4a1a0bad19..2bc6d0e2b5 100644
--- a/scripts/file_generator/main.ts
+++ b/scripts/file_generator/main.ts
@@ -1,6 +1,6 @@
 import { generateFileOfSize, toBytes } from '.';
 
-async function main() {
+async function main(): Promise<void> {
     const { path, sizeInBytes } = parseArgs();
 
     await generateFileOfSize(path, sizeInBytes);
@@ -32,7 +32,7 @@ function parseArgs(): { path: string; sizeInBytes: number } {
 }
 
 // Parse size from string with optional unit suffix (KB, MB, GB)
-function parseSize(sizeString: string) {
+function parseSize(sizeString: string): number {
     const sizeRegex = /^(\d+(?:\.\d+)?)([kmgb]?)$/i;
     const match = sizeString.match(sizeRegex);
     if (!match) {
diff --git a/scripts/hash_file/main.ts b/scripts/hash_file/main.ts
index 27b44e56f2..3c6228e411 100644
--- a/scripts/hash_file/main.ts
+++ b/scripts/hash_file/main.ts
@@ -1,6 +1,6 @@
 import { hashFile } from '.';
 
-async function main() {
+async function main(): Promise<void> {
     const args = process.argv.slice(2);
     const filePath = args[0];
     const fileHash = await hashFile(filePath);
diff --git a/scripts/reorder_dfx_json.js b/scripts/reorder_dfx_json.js
index 22d058a18f..6f0e0fb54c 100644
--- a/scripts/reorder_dfx_json.js
+++ b/scripts/reorder_dfx_json.js
@@ -1,3 +1,4 @@
+/* eslint-disable @typescript-eslint/explicit-function-return-type */
 // eslint-disable-next-line @typescript-eslint/no-var-requires
 const fs = require('fs-extra');
 // eslint-disable-next-line @typescript-eslint/no-var-requires
diff --git a/scripts/simplify_tsconfig.js b/scripts/simplify_tsconfig.js
index 84822794c2..b1f2c8485b 100644
--- a/scripts/simplify_tsconfig.js
+++ b/scripts/simplify_tsconfig.js
@@ -1,3 +1,4 @@
+/* eslint-disable @typescript-eslint/explicit-function-return-type */
 // eslint-disable-next-line @typescript-eslint/no-var-requires
 const fs = require('fs-extra');
 // eslint-disable-next-line @typescript-eslint/no-var-requires
diff --git a/scripts/update_dfx_json_main.js b/scripts/update_dfx_json_main.js
index 6f4d5c74fb..07bf0b9e23 100644
--- a/scripts/update_dfx_json_main.js
+++ b/scripts/update_dfx_json_main.js
@@ -1,3 +1,4 @@
+/* eslint-disable @typescript-eslint/explicit-function-return-type */
 // eslint-disable-next-line @typescript-eslint/no-var-requires
 const fs = require('fs');
 // eslint-disable-next-line @typescript-eslint/no-var-requires
diff --git a/src/compiler/compile_rust_code.ts b/src/compiler/compile_rust_code.ts
index a3a90f5b1c..8507c6f7be 100644
--- a/src/compiler/compile_rust_code.ts
+++ b/src/compiler/compile_rust_code.ts
@@ -7,7 +7,7 @@ export function compileRustCode(
     canisterName: string,
     stdio: IOType,
     nativeCompilation: boolean
-) {
+): void {
     if (nativeCompilation === true) {
         compileRustCodeNatively(canisterName, stdio);
     } else {
@@ -19,7 +19,7 @@ function compileRustCodeWithPodman(
     dockerContainerName: string,
     canisterName: string,
     stdio: IOType
-) {
+): void {
     execSyncPretty(
         `podman exec ${dockerContainerName} rm -rf /.azle/${canisterName}`,
         stdio
@@ -53,7 +53,7 @@ function compileRustCodeWithPodman(
     );
 }
 
-function compileRustCodeNatively(canisterName: string, stdio: IOType) {
+function compileRustCodeNatively(canisterName: string, stdio: IOType): void {
     execSyncPretty(
         `CARGO_TARGET_DIR=target cargo build --target wasm32-wasi --manifest-path .azle/${canisterName}/canister/Cargo.toml --release`,
         stdio
diff --git a/src/compiler/compile_rust_code_with_candid_and_compiler_info.ts b/src/compiler/compile_rust_code_with_candid_and_compiler_info.ts
index 165cbde8f8..293b878b33 100644
--- a/src/compiler/compile_rust_code_with_candid_and_compiler_info.ts
+++ b/src/compiler/compile_rust_code_with_candid_and_compiler_info.ts
@@ -13,7 +13,7 @@ export function compileRustCodeWithCandidAndCompilerInfo(
     canisterName: string,
     stdioType: IOType,
     nativeCompilation: boolean
-) {
+): void {
     // This is for the Rust canister to have access to the candid file
     writeFileSync(rustStagingCandidPath, candid);
 
diff --git a/src/compiler/custom_js_modules/perf_hooks.ts b/src/compiler/custom_js_modules/perf_hooks.ts
index 6a6b372e08..c67d214e7c 100644
--- a/src/compiler/custom_js_modules/perf_hooks.ts
+++ b/src/compiler/custom_js_modules/perf_hooks.ts
@@ -4,7 +4,7 @@
 // TODO it should be pretty easy and a good way to get started in the repo
 
 const performance = {
-    now: () => new Date().getTime()
+    now: (): number => new Date().getTime()
 };
 
 export { performance };
diff --git a/src/compiler/file_uploader/expand_paths.ts b/src/compiler/file_uploader/expand_paths.ts
index bf24dc0fa5..1ec7e3ac57 100644
--- a/src/compiler/file_uploader/expand_paths.ts
+++ b/src/compiler/file_uploader/expand_paths.ts
@@ -3,7 +3,9 @@ import { join } from 'path';
 
 import { Dest, Src } from '.';
 
-export async function expandPaths(paths: [Src, Dest][]) {
+export async function expandPaths(
+    paths: [Src, Dest][]
+): Promise<[string, string][]> {
     return paths.reduce(
         async (accPromise: Promise<[Src, Dest][]>, [srcPath, destPath]) => {
             const acc = await accPromise;
diff --git a/src/compiler/file_uploader/index.ts b/src/compiler/file_uploader/index.ts
index 4f0d99d25f..848ec8468f 100644
--- a/src/compiler/file_uploader/index.ts
+++ b/src/compiler/file_uploader/index.ts
@@ -8,7 +8,10 @@ import { createActor } from './uploader_actor';
 export type Src = string;
 export type Dest = string;
 
-export async function uploadFiles(canisterName: string, paths: [Src, Dest][]) {
+export async function uploadFiles(
+    canisterName: string,
+    paths: [Src, Dest][]
+): Promise<void> {
     if (paths.length === 0) {
         return;
     }
diff --git a/src/compiler/file_uploader/on_before_exit.ts b/src/compiler/file_uploader/on_before_exit.ts
index d7097762da..d88a51b6f5 100644
--- a/src/compiler/file_uploader/on_before_exit.ts
+++ b/src/compiler/file_uploader/on_before_exit.ts
@@ -3,7 +3,7 @@ import { getListOfIncompleteFiles } from './incomplete_files';
 import { getOngoingHashingJobs, OngoingHashingJob } from './ongoing_hashes';
 import { UploaderActor } from './uploader_actor';
 
-export function onBeforeExit(paths: [Src, Dest][], actor: UploaderActor) {
+export function onBeforeExit(paths: [Src, Dest][], actor: UploaderActor): void {
     let hashingComplete = false;
     let cleanUpComplete = false;
     let ongoingHashingJobs: OngoingHashingJob[] = [];
@@ -40,7 +40,10 @@ export function onBeforeExit(paths: [Src, Dest][], actor: UploaderActor) {
     });
 }
 
-async function cleanup(paths: [Src, Dest][], actor: UploaderActor) {
+async function cleanup(
+    paths: [Src, Dest][],
+    actor: UploaderActor
+): Promise<void> {
     const incompleteFiles = await getListOfIncompleteFiles(paths, actor);
     for (const [_, path] of incompleteFiles) {
         await actor.clear_file_and_info(path);
diff --git a/src/compiler/file_uploader/ongoing_hashes.ts b/src/compiler/file_uploader/ongoing_hashes.ts
index 6374e9b8f0..77cd0c9eac 100644
--- a/src/compiler/file_uploader/ongoing_hashes.ts
+++ b/src/compiler/file_uploader/ongoing_hashes.ts
@@ -92,7 +92,7 @@ function updateBytes(
     };
 }
 
-function reportOngoingHashingJobs(ongoingHashInfo: OngoingHashingJob[]) {
+function reportOngoingHashingJobs(ongoingHashInfo: OngoingHashingJob[]): void {
     for (const hashInfo of ongoingHashInfo) {
         const percent =
             (Number(hashInfo.bytesHashed) / Number(hashInfo.totalBytes)) * 100;
@@ -101,7 +101,7 @@ function reportOngoingHashingJobs(ongoingHashInfo: OngoingHashingJob[]) {
     console.info();
 }
 
-function reportIncompleteHashingJobs(paths: [Src, Dest][]) {
+function reportIncompleteHashingJobs(paths: [Src, Dest][]): void {
     console.info(
         `Missing hashes for ${paths.length} files:\n${paths.join('\n')}.`
     );
diff --git a/src/compiler/file_uploader/upload_file.ts b/src/compiler/file_uploader/upload_file.ts
index c69e5cdd91..9328dabdf0 100644
--- a/src/compiler/file_uploader/upload_file.ts
+++ b/src/compiler/file_uploader/upload_file.ts
@@ -10,7 +10,7 @@ export async function uploadFile(
     destPath: Dest,
     chunkSize: number,
     actor: UploaderActor
-) {
+): Promise<void> {
     if (!(await shouldBeUploaded(srcPath, destPath, actor))) {
         return;
     }
@@ -56,7 +56,7 @@ export async function uploadFile(
     console.info();
 }
 
-async function throttle() {
+async function throttle(): Promise<void> {
     // We can only process about 4Mib per second. So if chunks are about
     // 2 MiB or less then we can only send off two per second.
     if (process.env.DFX_NETWORK === 'ic') {
diff --git a/src/compiler/file_watcher/file_watcher.ts b/src/compiler/file_watcher/file_watcher.ts
index 0912d11763..1864e1543d 100644
--- a/src/compiler/file_watcher/file_watcher.ts
+++ b/src/compiler/file_watcher/file_watcher.ts
@@ -56,7 +56,7 @@ async function reloadJs(
     reloadedJsPath: string,
     mainPath: string,
     wasmedgeQuickJsPath: string
-) {
+): Promise<void> {
     const canisterJavaScriptResult = await getCanisterJavaScript(
         mainPath,
         wasmedgeQuickJsPath,
diff --git a/src/compiler/file_watcher/setup_file_watcher.ts b/src/compiler/file_watcher/setup_file_watcher.ts
index cd30d0ca8d..0f483b2a4e 100644
--- a/src/compiler/file_watcher/setup_file_watcher.ts
+++ b/src/compiler/file_watcher/setup_file_watcher.ts
@@ -12,7 +12,7 @@ export function setupFileWatcher(
     esmAliases: Record<string, string>,
     esmExternals: string[],
     canisterName: string
-) {
+): void {
     try {
         // TODO should we check that this was successful in killing
         // TODO the process and then warn the user if not?
diff --git a/src/compiler/generate_candid_and_canister_methods.ts b/src/compiler/generate_candid_and_canister_methods.ts
index 2f6cd883ab..47bec72414 100644
--- a/src/compiler/generate_candid_and_canister_methods.ts
+++ b/src/compiler/generate_candid_and_canister_methods.ts
@@ -11,23 +11,23 @@ export function generateCandidAndCanisterMethods(wasmFilePath: string): {
     const wasmModule = new WebAssembly.Module(wasmBuffer);
     const wasmInstance = new WebAssembly.Instance(wasmModule, {
         ic0: {
-            accept_message: () => {},
-            call_cycles_add: () => {},
-            call_cycles_add128: () => {},
-            call_data_append: () => {},
-            call_new: () => {},
-            call_on_cleanup: () => {},
-            call_perform: () => {},
-            canister_cycle_balance: () => {},
-            canister_cycle_balance128: () => {},
-            canister_self_copy: () => {},
-            canister_self_size: () => {},
-            canister_version: () => {},
-            certified_data_set: () => {},
-            data_certificate_copy: () => {},
-            data_certificate_present: () => {},
-            data_certificate_size: () => {},
-            debug_print: (ptr: number, len: number) => {
+            accept_message: (): void => {},
+            call_cycles_add: (): void => {},
+            call_cycles_add128: (): void => {},
+            call_data_append: (): void => {},
+            call_new: (): void => {},
+            call_on_cleanup: (): void => {},
+            call_perform: (): void => {},
+            canister_cycle_balance: (): void => {},
+            canister_cycle_balance128: (): void => {},
+            canister_self_copy: (): void => {},
+            canister_self_size: (): void => {},
+            canister_version: (): void => {},
+            certified_data_set: (): void => {},
+            data_certificate_copy: (): void => {},
+            data_certificate_present: (): void => {},
+            data_certificate_size: (): void => {},
+            debug_print: (ptr: number, len: number): void => {
                 const memory = new Uint8Array(
                     (wasmInstance.exports.memory as any).buffer,
                     ptr,
@@ -36,38 +36,38 @@ export function generateCandidAndCanisterMethods(wasmFilePath: string): {
                 const message = new TextDecoder('utf8').decode(memory);
                 console.log(message);
             },
-            global_timer_set: () => {},
-            instruction_counter: () => {},
-            is_controller: () => {},
-            msg_arg_data_copy: () => {},
-            msg_arg_data_size: () => {},
-            msg_caller_copy: () => {},
-            msg_caller_size: () => {},
-            msg_cycles_accept: () => {},
-            msg_cycles_accept128: () => {},
-            msg_cycles_available: () => {},
-            msg_cycles_available128: () => {},
-            msg_cycles_refunded: () => {},
-            msg_cycles_refunded128: () => {},
-            msg_method_name_copy: () => {},
-            msg_method_name_size: () => {},
-            msg_reject_code: () => {},
-            msg_reject_msg_copy: () => {},
-            msg_reject_msg_size: () => {},
-            msg_reject: () => {},
-            msg_reply_data_append: () => {},
-            msg_reply: () => {},
-            performance_counter: () => {},
-            stable_grow: () => {},
-            stable_read: () => {},
-            stable_size: () => {},
-            stable_write: () => {},
-            stable64_grow: () => {},
-            stable64_read: () => {},
-            stable64_size: () => {},
-            stable64_write: () => {},
+            global_timer_set: (): void => {},
+            instruction_counter: (): void => {},
+            is_controller: (): void => {},
+            msg_arg_data_copy: (): void => {},
+            msg_arg_data_size: (): void => {},
+            msg_caller_copy: (): void => {},
+            msg_caller_size: (): void => {},
+            msg_cycles_accept: (): void => {},
+            msg_cycles_accept128: (): void => {},
+            msg_cycles_available: (): void => {},
+            msg_cycles_available128: (): void => {},
+            msg_cycles_refunded: (): void => {},
+            msg_cycles_refunded128: (): void => {},
+            msg_method_name_copy: (): void => {},
+            msg_method_name_size: (): void => {},
+            msg_reject_code: (): void => {},
+            msg_reject_msg_copy: (): void => {},
+            msg_reject_msg_size: (): void => {},
+            msg_reject: (): void => {},
+            msg_reply_data_append: (): void => {},
+            msg_reply: (): void => {},
+            performance_counter: (): void => {},
+            stable_grow: (): void => {},
+            stable_read: (): void => {},
+            stable_size: (): void => {},
+            stable_write: (): void => {},
+            stable64_grow: (): void => {},
+            stable64_read: (): void => {},
+            stable64_size: (): void => {},
+            stable64_write: (): void => {},
             time: () => 0n,
-            trap: () => {}
+            trap: (): void => {}
         }
         // env: {
         //     azle_log(ptr: number, len: number) {
diff --git a/src/compiler/get_consumer_config.ts b/src/compiler/get_consumer_config.ts
index 1b5d7a2404..83824b8170 100644
--- a/src/compiler/get_consumer_config.ts
+++ b/src/compiler/get_consumer_config.ts
@@ -147,7 +147,7 @@ function getConsumerConfig(
     return canisterConfig.custom?.openValueSharing;
 }
 
-function logWarningPeriod(consumerConfig?: ConsumerConfig) {
+function logWarningPeriod(consumerConfig?: ConsumerConfig): void {
     if (consumerConfig?.period !== undefined) {
         console.warn(
             yellow(
diff --git a/src/compiler/handle_cli.ts b/src/compiler/handle_cli.ts
index a9aae86f0d..231af0e7fb 100644
--- a/src/compiler/handle_cli.ts
+++ b/src/compiler/handle_cli.ts
@@ -49,11 +49,11 @@ export function handleCli(
     return false;
 }
 
-function handleCommandNew() {
+function handleCommandNew(): void {
     generateNewAzleProject(azleVersion);
 }
 
-function handleCommandDockerfileHash(dockerfileHash: string) {
+function handleCommandDockerfileHash(dockerfileHash: string): void {
     execSyncPretty(`echo -n "${dockerfileHash}"`, 'inherit');
 }
 
@@ -61,7 +61,7 @@ function handleCommandClean(
     stdioType: IOType,
     dockerImagePrefix: string,
     dockerContainerPrefix: string
-) {
+): void {
     rmSync(GLOBAL_AZLE_CONFIG_DIR, {
         recursive: true,
         force: true
@@ -98,7 +98,7 @@ function handleCommandClean(
     console.info(`azle images removed`);
 }
 
-async function handleUploadAssets() {
+async function handleUploadAssets(): Promise<void> {
     const canisterName = process.argv[3];
     const srcPath = process.argv[4];
     const destPath = process.argv[5];
@@ -106,6 +106,6 @@ async function handleUploadAssets() {
     await uploadFiles(canisterName, filesToUpload);
 }
 
-function handleVersionCommand() {
+function handleVersionCommand(): void {
     console.info(azleVersion);
 }
diff --git a/src/compiler/index.ts b/src/compiler/index.ts
index bf97983bf0..cd69efdb9b 100644
--- a/src/compiler/index.ts
+++ b/src/compiler/index.ts
@@ -21,7 +21,7 @@ import { CompilerInfo } from './utils/types';
 
 azle();
 
-async function azle() {
+async function azle(): Promise<void> {
     // We must run this before getNamesBeforeCli because
     // any dfx commands require the azle extension to be installed
     if (process.argv[2] === 'install-dfx-extension') {
@@ -155,7 +155,7 @@ async function azle() {
     logSuccess(canisterName, canisterId, replicaWebServerPort);
 }
 
-function createAzleDirectories() {
+function createAzleDirectories(): void {
     mkdirSync(GLOBAL_AZLE_CONFIG_DIR, { recursive: true });
     mkdirSync('.azle', { recursive: true });
 }
@@ -163,7 +163,7 @@ function createAzleDirectories() {
 // TODO this is just temporary
 // TODO until we either make azle an official extension in the DFINITY dfx extensions repo
 // TODO or we have a better way for the developer to install the extension locally
-function installDfxExtension(stdioType: IOType) {
+function installDfxExtension(stdioType: IOType): void {
     const dfxExtensionDirectoryPath = join(AZLE_PACKAGE_PATH, 'dfx_extension');
     execSyncPretty(
         `cd ${dfxExtensionDirectoryPath} && ./install.sh`,
@@ -175,7 +175,7 @@ function addCanisterDidToAssets(
     canisterPath: string,
     canisterName: string,
     candid: string
-) {
+): void {
     writeFileSync(
         join(
             canisterPath,
diff --git a/src/compiler/new_command.ts b/src/compiler/new_command.ts
index 4786fb4307..aa085404c9 100644
--- a/src/compiler/new_command.ts
+++ b/src/compiler/new_command.ts
@@ -3,7 +3,7 @@ import { join } from 'path';
 
 import { AZLE_PACKAGE_PATH } from './utils/global_paths';
 
-export function generateNewAzleProject(azleVersion: string) {
+export function generateNewAzleProject(azleVersion: string): void {
     if (process.argv[3] === undefined) {
         console.error('You must provide a name for your Azle project');
         return;
diff --git a/src/compiler/prepare_docker_image.ts b/src/compiler/prepare_docker_image.ts
index 141ccf1336..8a56ba557c 100644
--- a/src/compiler/prepare_docker_image.ts
+++ b/src/compiler/prepare_docker_image.ts
@@ -13,7 +13,7 @@ export function prepareDockerImage(
     dockerImagePathTarGz: string,
     dockerContainerName: string,
     wasmedgeQuickJsPath: string
-) {
+): void {
     initAndStartVm(stdioType);
 
     loadImage(
@@ -31,7 +31,7 @@ export function prepareDockerImage(
     );
 }
 
-function initAndStartVm(stdioType: IOType) {
+function initAndStartVm(stdioType: IOType): void {
     // TODO I believe this is necessary for Mac
     // TODO If they do not need this command always run
     // TODO for example after restarts, then perhaps
@@ -57,7 +57,7 @@ function loadImage(
     dockerImageName: string,
     dockerImagePathTar: string,
     dockerImagePathTarGz: string
-) {
+): void {
     const imageHasAlreadyBeenLoaded = hasImageAlreadyBeenLoaded(
         stdioType,
         dockerImageName
@@ -128,7 +128,7 @@ function loadExistingLocalImage(
 function buildAndLoadImageWithDockerfile(
     dockerImageName: string,
     dockerImagePathTar: string
-) {
+): void {
     console.info(yellow(`\nBuilding image...\n`));
 
     execSyncPretty(
@@ -150,7 +150,7 @@ function downloadAndLoadRemoteImage(
     dockerImageName: string,
     dockerImagePathTar: string,
     dockerImagePathTarGz: string
-) {
+): void {
     console.info(yellow(`\nDownloading image...\n`));
 
     execSyncPretty(
@@ -168,7 +168,7 @@ function createAndStartContainer(
     dockerImageName: string,
     dockerContainerName: string,
     wasmedgeQuickJsPath: string
-) {
+): void {
     execSyncPretty(
         `podman create --name ${dockerContainerName} ${dockerImageName} tail -f /dev/null || true`,
         stdioType
diff --git a/src/compiler/prepare_rust_staging_area.ts b/src/compiler/prepare_rust_staging_area.ts
index 04a2495b04..61c7ccc79c 100644
--- a/src/compiler/prepare_rust_staging_area.ts
+++ b/src/compiler/prepare_rust_staging_area.ts
@@ -14,7 +14,7 @@ export async function prepareRustStagingArea(
     canisterPath: string,
     canisterJavaScript: string,
     stdioType: IOType
-) {
+): Promise<void> {
     const workspaceCargoToml: Toml = generateWorkspaceCargoToml(
         canisterConfig.opt_level ?? '0'
     );
diff --git a/src/compiler/utils/global_paths.ts b/src/compiler/utils/global_paths.ts
index 3147728618..fcadef342f 100644
--- a/src/compiler/utils/global_paths.ts
+++ b/src/compiler/utils/global_paths.ts
@@ -8,6 +8,6 @@ export const GLOBAL_AZLE_CONFIG_DIR = resolve(
 
 export const AZLE_PACKAGE_PATH =
     require.main?.path ??
-    (() => {
+    ((): never => {
         throw new Error(`Azle: azle package path cannot be undefined`);
     })();
diff --git a/src/lib/candid/did_file/visitor/visit/service.ts b/src/lib/candid/did_file/visitor/visit/service.ts
index 433d7b1e44..b4c250d702 100644
--- a/src/lib/candid/did_file/visitor/visit/service.ts
+++ b/src/lib/candid/did_file/visitor/visit/service.ts
@@ -72,7 +72,7 @@ function getSystemMethod(
     didVisitor: DidVisitor,
     data: VisitorData
 ): [CandidDef[], CandidTypesDefs] {
-    const isInitFunction = (func: IDL.FuncClass) =>
+    const isInitFunction = (func: IDL.FuncClass): boolean =>
         func.annotations.includes(methodName);
     const result = extractCandid(
         data.systemFuncs
diff --git a/src/lib/candid/serde/visitors/visit/variant/azle_result.ts b/src/lib/candid/serde/visitors/visit/variant/azle_result.ts
index 63f0d90522..99851a105d 100644
--- a/src/lib/candid/serde/visitors/visit/variant/azle_result.ts
+++ b/src/lib/candid/serde/visitors/visit/variant/azle_result.ts
@@ -9,7 +9,7 @@ export function visitAzleResult(
     visitor: DecodeVisitor | EncodeVisitor,
     fields: [string, IDL.Type<any>][],
     data: VisitorData
-) {
+): Result<any, any> {
     if ('Ok' in data.js_data) {
         const OK_FIELD_INDEX = 0;
         const okField = fields[OK_FIELD_INDEX];
@@ -35,4 +35,5 @@ export function visitAzleResult(
             })
         );
     }
+    throw new Error('Invalid Result');
 }
diff --git a/src/lib/candid/serde/visitors/visit/variant/azle_variant.ts b/src/lib/candid/serde/visitors/visit/variant/azle_variant.ts
index 77563e81be..4c20271eb7 100644
--- a/src/lib/candid/serde/visitors/visit/variant/azle_variant.ts
+++ b/src/lib/candid/serde/visitors/visit/variant/azle_variant.ts
@@ -1,5 +1,6 @@
 import { IDL } from '@dfinity/candid';
 
+import { Variant } from '../../../../types/constructed';
 import { DecodeVisitor } from '../../decode_visitor';
 import { EncodeVisitor } from '../../encode_visitor';
 import { VisitorData } from '../../types';
@@ -8,7 +9,7 @@ export function visitAzleVariant(
     visitor: DecodeVisitor | EncodeVisitor,
     fields: [string, IDL.Type<any>][],
     data: VisitorData
-) {
+): Variant<any> {
     const candidFields = fields.reduce((acc, [memberName, memberIdl]) => {
         const fieldData = data.js_data[memberName];
         const fieldClass = data.candidType[memberName];
diff --git a/src/lib/candid/types/constructed/blob.ts b/src/lib/candid/types/constructed/blob.ts
index fea080d021..8df7949404 100644
--- a/src/lib/candid/types/constructed/blob.ts
+++ b/src/lib/candid/types/constructed/blob.ts
@@ -9,15 +9,15 @@ export class AzleBlob {
 
     static tsType: blob;
 
-    static toBytes(data: any) {
+    static toBytes(data: blob): Uint8Array {
         return encode(this, data);
     }
 
-    static fromBytes(bytes: Uint8Array) {
-        return decode(this, bytes);
+    static fromBytes(bytes: Uint8Array): blob {
+        return decode(this, bytes) as blob;
     }
 
-    static getIdl() {
+    static getIdl(): IDL.VecClass<number | bigint> {
         return IDL.Vec(IDL.Nat8);
     }
 }
diff --git a/src/lib/candid/types/constructed/opt.ts b/src/lib/candid/types/constructed/opt.ts
index b0d602f27c..01ee632c5f 100644
--- a/src/lib/candid/types/constructed/opt.ts
+++ b/src/lib/candid/types/constructed/opt.ts
@@ -18,7 +18,7 @@ export type Opt<T> = RequireExactlyOne<{ Some: T; None: null }>;
  * @param value - the value to be wrapped
  * @returns a `Some` {@link Opt} containing the provided value
  */
-export function Some<T>(value: T) {
+export function Some<T>(value: T): Opt<T> {
     return { Some: value };
 }
 
@@ -26,7 +26,7 @@ export function Some<T>(value: T) {
 export const None = { None: null };
 
 // TODO what happens if we pass something to Opt() that can't be converted to CandidClass?
-export function Opt<T extends CandidType>(t: T) {
+export function Opt<T extends CandidType>(t: T): AzleOpt<T> {
     return new AzleOpt<T>(t);
 }
 
@@ -42,7 +42,7 @@ export class AzleOpt<T> {
     _azleKind = 'AzleOpt' as const;
     static _azleKind = 'AzleOpt' as const;
 
-    toBytes(data: any) {
+    toBytes(data: any): Uint8Array {
         return encode(this, data);
     }
 
@@ -50,7 +50,7 @@ export class AzleOpt<T> {
         return decode(this, bytes);
     }
 
-    getIdl(parents: Parent[]) {
+    getIdl(parents: Parent[]): IDL.OptClass<T> {
         return IDL.Opt(toIdl(this.innerType, parents));
     }
 }
diff --git a/src/lib/candid/types/constructed/record.ts b/src/lib/candid/types/constructed/record.ts
index cfc1ea85e0..0142f753df 100644
--- a/src/lib/candid/types/constructed/record.ts
+++ b/src/lib/candid/types/constructed/record.ts
@@ -17,13 +17,13 @@ export function Record<
         tsType: {} as {
             [K in keyof T]: TypeMapping<T[K]>;
         },
-        toBytes(data: any) {
+        toBytes(data: any): Uint8Array {
             return encode(this, data);
         },
         fromBytes(bytes: Uint8Array) {
             return decode(this, bytes);
         },
-        getIdl(parents: Parent[]) {
+        getIdl(parents: Parent[]): IDL.RecordClass {
             return IDL.Record(toIdlMap(obj as CandidMap, parents));
         }
     };
diff --git a/src/lib/candid/types/constructed/tuple.ts b/src/lib/candid/types/constructed/tuple.ts
index bb52cc9144..fc40b197e3 100644
--- a/src/lib/candid/types/constructed/tuple.ts
+++ b/src/lib/candid/types/constructed/tuple.ts
@@ -20,7 +20,7 @@ export class AzleTuple<T extends any[]> {
     _azleKind = 'AzleTuple' as const;
     static _azleKind = 'AzleTuple' as const;
 
-    toBytes(data: any) {
+    toBytes(data: any): Uint8Array {
         return encode(this, data);
     }
 
@@ -28,7 +28,7 @@ export class AzleTuple<T extends any[]> {
         return decode(this, bytes);
     }
 
-    getIdl(parents: Parent[]) {
+    getIdl(parents: Parent[]): IDL.TupleClass<any> {
         const idls = this.innerTypes.map((value) => {
             return toIdl(value, parents);
         });
@@ -36,7 +36,7 @@ export class AzleTuple<T extends any[]> {
     }
 }
 
-export function Tuple<T extends CandidType[]>(...types: T) {
+export function Tuple<T extends CandidType[]>(...types: T): AzleTuple<T> {
     return new AzleTuple<T>(types);
 }
 export type Tuple<T> = T;
diff --git a/src/lib/candid/types/constructed/variant.ts b/src/lib/candid/types/constructed/variant.ts
index 1e3a6aee60..296a203489 100644
--- a/src/lib/candid/types/constructed/variant.ts
+++ b/src/lib/candid/types/constructed/variant.ts
@@ -22,13 +22,13 @@ export function Variant<
     return {
         ...obj,
         tsType: {} as Variant<T>,
-        toBytes(data: any) {
+        toBytes(data: any): Uint8Array {
             return encode(this, data);
         },
         fromBytes(bytes: Uint8Array) {
             return decode(this, bytes);
         },
-        getIdl(parents: any) {
+        getIdl(parents: any): IDL.VariantClass {
             return IDL.Variant(toIdlMap(obj as CandidMap, parents));
         }
     };
diff --git a/src/lib/candid/types/constructed/vec.ts b/src/lib/candid/types/constructed/vec.ts
index cdb3b0acc1..c74fa14425 100644
--- a/src/lib/candid/types/constructed/vec.ts
+++ b/src/lib/candid/types/constructed/vec.ts
@@ -18,15 +18,15 @@ export class AzleVec<T> {
     _azleKind = 'AzleVec' as const;
     static _azleKind = 'AzleVec' as const;
 
-    toBytes(data: any) {
+    toBytes(data: T[]): Uint8Array {
         return encode(this, data);
     }
 
-    fromBytes(bytes: Uint8Array) {
-        return decode(this, bytes);
+    fromBytes(bytes: Uint8Array): T[] {
+        return decode<T[]>(this, bytes) as T[];
     }
 
-    getIdl(parents: Parent[]) {
+    getIdl(parents: Parent[]): IDL.VecClass<T> {
         return IDL.Vec(toIdl(this.innerType, parents));
     }
 }
diff --git a/src/lib/candid/types/primitive/bool.ts b/src/lib/candid/types/primitive/bool.ts
index 9ccb98a530..9cdf586b3b 100644
--- a/src/lib/candid/types/primitive/bool.ts
+++ b/src/lib/candid/types/primitive/bool.ts
@@ -9,15 +9,15 @@ export class AzleBool {
 
     static tsType: bool;
 
-    static toBytes(data: any) {
+    static toBytes(data: bool): Uint8Array {
         return encode(this, data);
     }
 
-    static fromBytes(bytes: Uint8Array) {
-        return decode(this, bytes);
+    static fromBytes(bytes: Uint8Array): bool {
+        return decode<bool>(this, bytes) as bool;
     }
 
-    static getIdl() {
+    static getIdl(): IDL.BoolClass {
         return IDL.Bool;
     }
 }
diff --git a/src/lib/candid/types/primitive/empty.ts b/src/lib/candid/types/primitive/empty.ts
index 6ab13069fc..5137aedaa9 100644
--- a/src/lib/candid/types/primitive/empty.ts
+++ b/src/lib/candid/types/primitive/empty.ts
@@ -9,15 +9,15 @@ export class AzleEmpty {
 
     static tsType: empty;
 
-    static toBytes(data: any) {
+    static toBytes(data: empty): Uint8Array {
         return encode(this, data);
     }
 
-    static fromBytes(bytes: Uint8Array) {
-        return decode(this, bytes);
+    static fromBytes(bytes: Uint8Array): empty {
+        return decode<empty>(this, bytes) as empty;
     }
 
-    static getIdl() {
+    static getIdl(): IDL.EmptyClass {
         return IDL.Empty;
     }
 }
diff --git a/src/lib/candid/types/primitive/floats/float32.ts b/src/lib/candid/types/primitive/floats/float32.ts
index f53b1662f0..3fe3098155 100644
--- a/src/lib/candid/types/primitive/floats/float32.ts
+++ b/src/lib/candid/types/primitive/floats/float32.ts
@@ -9,15 +9,15 @@ export class AzleFloat32 {
 
     static tsType: float32;
 
-    static toBytes(data: any) {
+    static toBytes(data: float32): Uint8Array {
         return encode(this, data);
     }
 
-    static fromBytes(bytes: Uint8Array) {
-        return decode(this, bytes);
+    static fromBytes(bytes: Uint8Array): float32 {
+        return decode<float32>(this, bytes) as float32;
     }
 
-    static getIdl() {
+    static getIdl(): IDL.FloatClass {
         return IDL.Float32;
     }
 }
diff --git a/src/lib/candid/types/primitive/floats/float64.ts b/src/lib/candid/types/primitive/floats/float64.ts
index 53465a8f80..2a7751911e 100644
--- a/src/lib/candid/types/primitive/floats/float64.ts
+++ b/src/lib/candid/types/primitive/floats/float64.ts
@@ -9,15 +9,15 @@ export class AzleFloat64 {
 
     static tsType: float64;
 
-    static toBytes(data: any) {
+    static toBytes(data: float64): Uint8Array {
         return encode(this, data);
     }
 
-    static fromBytes(bytes: Uint8Array) {
-        return decode(this, bytes);
+    static fromBytes(bytes: Uint8Array): float64 {
+        return decode<float64>(this, bytes) as float64;
     }
 
-    static getIdl() {
+    static getIdl(): IDL.FloatClass {
         return IDL.Float64;
     }
 }
diff --git a/src/lib/candid/types/primitive/ints/int.ts b/src/lib/candid/types/primitive/ints/int.ts
index c84f61197c..63cee2f4a6 100644
--- a/src/lib/candid/types/primitive/ints/int.ts
+++ b/src/lib/candid/types/primitive/ints/int.ts
@@ -9,15 +9,15 @@ export class AzleInt {
 
     static tsType: int;
 
-    static toBytes(data: any) {
+    static toBytes(data: int): Uint8Array {
         return encode(this, data);
     }
 
-    static fromBytes(bytes: Uint8Array) {
-        return decode(this, bytes);
+    static fromBytes(bytes: Uint8Array): int {
+        return decode<int>(this, bytes) as int;
     }
 
-    static getIdl() {
+    static getIdl(): IDL.IntClass {
         return IDL.Int;
     }
 }
diff --git a/src/lib/candid/types/primitive/ints/int16.ts b/src/lib/candid/types/primitive/ints/int16.ts
index e5d65827c3..5ccd935c53 100644
--- a/src/lib/candid/types/primitive/ints/int16.ts
+++ b/src/lib/candid/types/primitive/ints/int16.ts
@@ -9,15 +9,15 @@ export class AzleInt16 {
 
     static tsType: int16;
 
-    static toBytes(data: any) {
+    static toBytes(data: int16): Uint8Array {
         return encode(this, data);
     }
 
-    static fromBytes(bytes: Uint8Array) {
-        return decode(this, bytes);
+    static fromBytes(bytes: Uint8Array): int16 {
+        return decode<int16>(this, bytes) as int16;
     }
 
-    static getIdl() {
+    static getIdl(): IDL.FixedIntClass {
         return IDL.Int16;
     }
 }
diff --git a/src/lib/candid/types/primitive/ints/int32.ts b/src/lib/candid/types/primitive/ints/int32.ts
index 0e29281e62..52f905b87f 100644
--- a/src/lib/candid/types/primitive/ints/int32.ts
+++ b/src/lib/candid/types/primitive/ints/int32.ts
@@ -9,15 +9,15 @@ export class AzleInt32 {
 
     static tsType: int32;
 
-    static toBytes(data: any) {
+    static toBytes(data: int32): Uint8Array {
         return encode(this, data);
     }
 
-    static fromBytes(bytes: Uint8Array) {
-        return decode(this, bytes);
+    static fromBytes(bytes: Uint8Array): int32 {
+        return decode<int32>(this, bytes) as int32;
     }
 
-    static getIdl() {
+    static getIdl(): IDL.FixedIntClass {
         return IDL.Int32;
     }
 }
diff --git a/src/lib/candid/types/primitive/ints/int64.ts b/src/lib/candid/types/primitive/ints/int64.ts
index 1a43f9e3f3..fefd858261 100644
--- a/src/lib/candid/types/primitive/ints/int64.ts
+++ b/src/lib/candid/types/primitive/ints/int64.ts
@@ -9,15 +9,15 @@ export class AzleInt64 {
 
     static tsType: int64;
 
-    static toBytes(data: any) {
+    static toBytes(data: int64): Uint8Array {
         return encode(this, data);
     }
 
-    static fromBytes(bytes: Uint8Array) {
-        return decode(this, bytes);
+    static fromBytes(bytes: Uint8Array): int64 {
+        return decode<int64>(this, bytes) as int64;
     }
 
-    static getIdl() {
+    static getIdl(): IDL.FixedIntClass {
         return IDL.Int64;
     }
 }
diff --git a/src/lib/candid/types/primitive/ints/int8.ts b/src/lib/candid/types/primitive/ints/int8.ts
index e1a65ac4f3..58cda65adc 100644
--- a/src/lib/candid/types/primitive/ints/int8.ts
+++ b/src/lib/candid/types/primitive/ints/int8.ts
@@ -9,15 +9,15 @@ export class AzleInt8 {
 
     static tsType: int8;
 
-    static toBytes(data: any) {
+    static toBytes(data: int8): Uint8Array {
         return encode(this, data);
     }
 
-    static fromBytes(bytes: Uint8Array) {
-        return decode(this, bytes);
+    static fromBytes(bytes: Uint8Array): int8 {
+        return decode<int8>(this, bytes) as int8;
     }
 
-    static getIdl() {
+    static getIdl(): IDL.FixedIntClass {
         return IDL.Int8;
     }
 }
diff --git a/src/lib/candid/types/primitive/nats/nat.ts b/src/lib/candid/types/primitive/nats/nat.ts
index f8a451e810..586c316270 100644
--- a/src/lib/candid/types/primitive/nats/nat.ts
+++ b/src/lib/candid/types/primitive/nats/nat.ts
@@ -9,15 +9,15 @@ export class AzleNat {
 
     static tsType: nat;
 
-    static toBytes(data: any) {
+    static toBytes(data: nat): Uint8Array {
         return encode(this, data);
     }
 
-    static fromBytes(bytes: Uint8Array) {
-        return decode(this, bytes);
+    static fromBytes(bytes: Uint8Array): nat {
+        return decode(this, bytes) as nat;
     }
 
-    static getIdl() {
+    static getIdl(): IDL.NatClass {
         return IDL.Nat;
     }
 }
diff --git a/src/lib/candid/types/primitive/nats/nat16.ts b/src/lib/candid/types/primitive/nats/nat16.ts
index 097753a423..04fb4b59c2 100644
--- a/src/lib/candid/types/primitive/nats/nat16.ts
+++ b/src/lib/candid/types/primitive/nats/nat16.ts
@@ -9,15 +9,15 @@ export class AzleNat16 {
 
     static tsType: nat16;
 
-    static toBytes(data: any) {
+    static toBytes(data: nat16): Uint8Array {
         return encode(this, data);
     }
 
-    static fromBytes(bytes: Uint8Array) {
-        return decode(this, bytes);
+    static fromBytes(bytes: Uint8Array): nat16 {
+        return decode<nat16>(this, bytes) as nat16;
     }
 
-    static getIdl() {
+    static getIdl(): IDL.FixedNatClass {
         return IDL.Nat16;
     }
 }
diff --git a/src/lib/candid/types/primitive/nats/nat32.ts b/src/lib/candid/types/primitive/nats/nat32.ts
index 6bbe15d199..9c51b4b9bb 100644
--- a/src/lib/candid/types/primitive/nats/nat32.ts
+++ b/src/lib/candid/types/primitive/nats/nat32.ts
@@ -9,15 +9,15 @@ export class AzleNat32 {
 
     static tsType: nat32;
 
-    static toBytes(data: any) {
+    static toBytes(data: nat32): Uint8Array {
         return encode(this, data);
     }
 
-    static fromBytes(bytes: Uint8Array) {
-        return decode(this, bytes);
+    static fromBytes(bytes: Uint8Array): nat32 {
+        return decode<nat32>(this, bytes) as nat32;
     }
 
-    static getIdl() {
+    static getIdl(): IDL.FixedNatClass {
         return IDL.Nat32;
     }
 }
diff --git a/src/lib/candid/types/primitive/nats/nat64.ts b/src/lib/candid/types/primitive/nats/nat64.ts
index 234ccece51..3a9e3bfb4a 100644
--- a/src/lib/candid/types/primitive/nats/nat64.ts
+++ b/src/lib/candid/types/primitive/nats/nat64.ts
@@ -9,15 +9,15 @@ export class AzleNat64 {
 
     static tsType: nat64;
 
-    static toBytes(data: any) {
+    static toBytes(data: nat64): Uint8Array {
         return encode(this, data);
     }
 
-    static fromBytes(bytes: Uint8Array) {
-        return decode(this, bytes);
+    static fromBytes(bytes: Uint8Array): nat64 {
+        return decode<nat64>(this, bytes) as nat64;
     }
 
-    static getIdl() {
+    static getIdl(): IDL.FixedNatClass {
         return IDL.Nat64;
     }
 }
diff --git a/src/lib/candid/types/primitive/nats/nat8.ts b/src/lib/candid/types/primitive/nats/nat8.ts
index 55f2447f98..6b6fee1ee7 100644
--- a/src/lib/candid/types/primitive/nats/nat8.ts
+++ b/src/lib/candid/types/primitive/nats/nat8.ts
@@ -9,15 +9,15 @@ export class AzleNat8 {
 
     static tsType: nat8;
 
-    static toBytes(data: any) {
+    static toBytes(data: nat8): Uint8Array {
         return encode(this, data);
     }
 
-    static fromBytes(bytes: Uint8Array) {
-        return decode(this, bytes);
+    static fromBytes(bytes: Uint8Array): nat8 {
+        return decode<nat8>(this, bytes) as nat8;
     }
 
-    static getIdl() {
+    static getIdl(): IDL.FixedNatClass {
         return IDL.Nat8;
     }
 }
diff --git a/src/lib/candid/types/primitive/null.ts b/src/lib/candid/types/primitive/null.ts
index 3f7d5785dd..c7c49c4701 100644
--- a/src/lib/candid/types/primitive/null.ts
+++ b/src/lib/candid/types/primitive/null.ts
@@ -9,15 +9,15 @@ export class AzleNull {
 
     static tsType: Null;
 
-    static toBytes(data: any) {
+    static toBytes(data: Null): Uint8Array {
         return encode(this, data);
     }
 
-    static fromBytes(bytes: Uint8Array) {
-        return decode(this, bytes);
+    static fromBytes(bytes: Uint8Array): Null {
+        return decode<Null>(this, bytes) as Null;
     }
 
-    static getIdl() {
+    static getIdl(): IDL.NullClass {
         return IDL.Null;
     }
 }
diff --git a/src/lib/candid/types/primitive/reserved.ts b/src/lib/candid/types/primitive/reserved.ts
index 5e69151e6b..7409eba949 100644
--- a/src/lib/candid/types/primitive/reserved.ts
+++ b/src/lib/candid/types/primitive/reserved.ts
@@ -9,15 +9,15 @@ export class AzleReserved {
 
     static tsType: reserved;
 
-    static toBytes(data: any) {
+    static toBytes(data: any): Uint8Array {
         return encode(this, data);
     }
 
-    static fromBytes(bytes: Uint8Array) {
+    static fromBytes(bytes: Uint8Array): any {
         return decode(this, bytes);
     }
 
-    static getIdl() {
+    static getIdl(): IDL.ReservedClass {
         return IDL.Reserved;
     }
 }
diff --git a/src/lib/candid/types/primitive/text.ts b/src/lib/candid/types/primitive/text.ts
index 6615948901..f549bc02b2 100644
--- a/src/lib/candid/types/primitive/text.ts
+++ b/src/lib/candid/types/primitive/text.ts
@@ -9,15 +9,15 @@ export class AzleText {
 
     static tsType: text;
 
-    static toBytes(data: any) {
+    static toBytes(data: string): Uint8Array {
         return encode(this, data);
     }
 
-    static fromBytes(bytes: Uint8Array) {
-        return decode(this, bytes);
+    static fromBytes(bytes: Uint8Array): string {
+        return decode<string>(this, bytes) as string;
     }
 
-    static getIdl() {
+    static getIdl(): IDL.TextClass {
         return IDL.Text;
     }
 }
diff --git a/src/lib/candid/types/primitive/void.ts b/src/lib/candid/types/primitive/void.ts
index 12abe87530..5817c3fda8 100644
--- a/src/lib/candid/types/primitive/void.ts
+++ b/src/lib/candid/types/primitive/void.ts
@@ -9,12 +9,12 @@ export class AzleVoid {
 
     static tsType: Void;
 
-    static toBytes(data: any) {
+    static toBytes(data: undefined): Uint8Array {
         return encode(this, data);
     }
 
-    static fromBytes(bytes: Uint8Array) {
-        return decode(this, bytes);
+    static fromBytes(bytes: Uint8Array): undefined {
+        return decode<undefined>(this, bytes) as undefined;
     }
 
     static getIdl(): IDL.Type<any> {
diff --git a/src/lib/candid/types/reference/func.ts b/src/lib/candid/types/reference/func.ts
index 00e4a653f9..50c6c2b851 100644
--- a/src/lib/candid/types/reference/func.ts
+++ b/src/lib/candid/types/reference/func.ts
@@ -21,13 +21,13 @@ export function Func(
 ) {
     return {
         tsType: {} as Func,
-        toBytes(data: any) {
+        toBytes(data: Func): Uint8Array {
             return encode(this, data);
         },
-        fromBytes(bytes: Uint8Array) {
-            return decode(this, bytes);
+        fromBytes(bytes: Uint8Array): Func {
+            return decode<Func>(this, bytes) as Func;
         },
-        getIdl(parents: Parent[]) {
+        getIdl(parents: Parent[]): IDL.FuncClass {
             return IDL.Func(
                 toIdlArray(paramCandidTypes, parents),
                 toIdlArray(returnCandidTypes, parents),
diff --git a/src/lib/candid/types/reference/principal.ts b/src/lib/candid/types/reference/principal.ts
index 48d48d1ae7..894ebf2b9a 100644
--- a/src/lib/candid/types/reference/principal.ts
+++ b/src/lib/candid/types/reference/principal.ts
@@ -10,15 +10,15 @@ export class Principal extends DfinityPrincipal {
 
     static tsType: Principal;
 
-    static toBytes(data: any) {
+    static toBytes(data: DfinityPrincipal): Uint8Array {
         return encode(this, data);
     }
 
-    static fromBytes(bytes: Uint8Array) {
-        return decode(this, bytes);
+    static fromBytes(bytes: Uint8Array): DfinityPrincipal {
+        return decode<DfinityPrincipal>(this, bytes) as DfinityPrincipal;
     }
 
-    static getIdl(_parents: Parent[]) {
+    static getIdl(_parents: Parent[]): IDL.PrincipalClass {
         return IDL.Principal;
     }
 }
diff --git a/src/lib/candid/types/reference/service/canister_function/index.ts b/src/lib/candid/types/reference/service/canister_function/index.ts
index ff69900f90..f1371b8f59 100644
--- a/src/lib/candid/types/reference/service/canister_function/index.ts
+++ b/src/lib/candid/types/reference/service/canister_function/index.ts
@@ -68,7 +68,7 @@ function createGetIdlFunction(canisterOptions: CanisterOptions) {
         const serviceFunctionInfo = canisterOptions as ServiceFunctionInfo;
 
         // We don't want init, post upgrade, etc showing up in the idl
-        const isQueryOrUpdate = (mode: string) => {
+        const isQueryOrUpdate = (mode: string): boolean => {
             return mode === 'query' || mode === 'update';
         };
 
diff --git a/src/lib/candid/types/reference/service/canister_function/query_update.ts b/src/lib/candid/types/reference/service/canister_function/query_update.ts
index 3d35032cfb..6554d382ec 100644
--- a/src/lib/candid/types/reference/service/canister_function/query_update.ts
+++ b/src/lib/candid/types/reference/service/canister_function/query_update.ts
@@ -68,7 +68,7 @@ function createGlobalGuard(
 
     const guardName = `_azleGuard_${guardedMethodName}`;
 
-    globalThis._azleGuardFunctions[guardName] = () => {
+    globalThis._azleGuardFunctions[guardName] = (): void => {
         try {
             guard();
         } catch (error) {
diff --git a/src/lib/canister_methods/execute_method.ts b/src/lib/canister_methods/execute_method.ts
index e572f56131..7a66458c2e 100644
--- a/src/lib/canister_methods/execute_method.ts
+++ b/src/lib/canister_methods/execute_method.ts
@@ -12,7 +12,7 @@ export function executeMethod(
     paramCandidTypes: CandidType[],
     returnCandidType: CandidType,
     manual: boolean
-) {
+): void {
     const decodedArgs = decode(paramCandidTypes, args[0]);
 
     const result = getResult(decodedArgs, callback);
@@ -60,7 +60,7 @@ function getResult(args: any[], callback: any): any {
     }
 }
 
-function reportFinalInstructions() {
+function reportFinalInstructions(): void {
     if (process.env.AZLE_INSTRUCTION_COUNT === 'true') {
         console.log(`final instructions: ${ic.instructionCounter()}`);
     }
diff --git a/src/lib/canister_methods/is_async.ts b/src/lib/canister_methods/is_async.ts
index 5c077e7dbe..5c1bde827a 100644
--- a/src/lib/canister_methods/is_async.ts
+++ b/src/lib/canister_methods/is_async.ts
@@ -1,4 +1,4 @@
-export function isAsync(originalFunction: any) {
+export function isAsync(originalFunction: any): boolean {
     if (originalFunction[Symbol.toStringTag] === 'AsyncFunction') {
         return true;
     } else if (originalFunction.constructor.name === 'AsyncFunction') {
diff --git a/src/lib/canister_methods/methods/heartbeat.ts b/src/lib/canister_methods/methods/heartbeat.ts
index d1f59501f6..3a61eaa543 100644
--- a/src/lib/canister_methods/methods/heartbeat.ts
+++ b/src/lib/canister_methods/methods/heartbeat.ts
@@ -16,7 +16,7 @@ export function heartbeat(
     };
 }
 
-function executeHeartbeat(callback: any) {
+function executeHeartbeat(callback: any): void {
     const result = callback();
 
     if (
diff --git a/src/lib/canister_methods/methods/init.ts b/src/lib/canister_methods/methods/init.ts
index 0272d92fa3..d8ce93c4b2 100644
--- a/src/lib/canister_methods/methods/init.ts
+++ b/src/lib/canister_methods/methods/init.ts
@@ -17,7 +17,7 @@ export function init<
     const finalCallback =
         callback === undefined
             ? undefined
-            : (...args: any[]) => {
+            : (...args: any[]): void => {
                   executeMethod(
                       'init',
                       args,
diff --git a/src/lib/canister_methods/methods/inspect_message.ts b/src/lib/canister_methods/methods/inspect_message.ts
index 053996eaf6..cacb2eb76d 100644
--- a/src/lib/canister_methods/methods/inspect_message.ts
+++ b/src/lib/canister_methods/methods/inspect_message.ts
@@ -5,7 +5,7 @@ import { CanisterMethodInfo } from '../types/canister_method_info';
 export function inspectMessage(
     callback: () => void | Promise<void>
 ): CanisterMethodInfo<[], Void> {
-    const finalCallback = (...args: any[]) => {
+    const finalCallback = (...args: any[]): void => {
         executeMethod('inspectMessage', args, callback, [], Void, false);
     };
 
diff --git a/src/lib/canister_methods/methods/post_upgrade.ts b/src/lib/canister_methods/methods/post_upgrade.ts
index 5d32ea6836..6535d16b93 100644
--- a/src/lib/canister_methods/methods/post_upgrade.ts
+++ b/src/lib/canister_methods/methods/post_upgrade.ts
@@ -17,7 +17,7 @@ export function postUpgrade<
     const finalCallback =
         callback === undefined
             ? undefined
-            : (...args: any[]) => {
+            : (...args: any[]): void => {
                   executeMethod(
                       'postUpgrade',
                       args,
diff --git a/src/lib/canister_methods/methods/query.ts b/src/lib/canister_methods/methods/query.ts
index 24d22dfbee..57ec220689 100644
--- a/src/lib/canister_methods/methods/query.ts
+++ b/src/lib/canister_methods/methods/query.ts
@@ -22,7 +22,7 @@ export function query<
     const finalCallback =
         callback === undefined
             ? undefined
-            : (...args: any[]) => {
+            : (...args: any[]): void => {
                   executeMethod(
                       'query',
                       args,
diff --git a/src/lib/canister_methods/methods/update.ts b/src/lib/canister_methods/methods/update.ts
index b88e6a8981..892b38a308 100644
--- a/src/lib/canister_methods/methods/update.ts
+++ b/src/lib/canister_methods/methods/update.ts
@@ -21,7 +21,7 @@ export function update<
     const finalCallback =
         callback === undefined
             ? undefined
-            : (...args: any[]) => {
+            : (...args: any[]): void => {
                   executeMethod(
                       'update',
                       args,
diff --git a/src/lib/fetch/headers.ts b/src/lib/fetch/headers.ts
index 1d85c7ef1a..877b4b4e3b 100644
--- a/src/lib/fetch/headers.ts
+++ b/src/lib/fetch/headers.ts
@@ -4,7 +4,7 @@ export class AzleFetchHeaders {
         [key: string]: string;
     } = {};
 
-    [Symbol.iterator]() {
+    [Symbol.iterator](): IterableIterator<[string, string]> {
         return this.entries();
     }
 
@@ -29,16 +29,16 @@ export class AzleFetchHeaders {
 
     // TODO append seems a bit complicated to implement because we have to know which
     // TODO headers can accept multiple values
-    append() {
+    append(): void {
         throw new Error(`AzleFetchHeaders: append is not yet implemented`);
     }
 
     // TODO we do not throw here like the documentation says we should
-    delete(name: string) {
+    delete(name: string): void {
         delete this.headers[name];
     }
 
-    entries() {
+    entries(): IterableIterator<[string, string]> {
         return Object.entries(this.headers)[Symbol.iterator]();
     }
 
@@ -49,13 +49,13 @@ export class AzleFetchHeaders {
             headers: AzleFetchHeaders
         ) => any,
         thisArg: any = this // TODO is this the correct this?
-    ) {
+    ): void {
         Object.entries(this.headers).forEach(([key, value]) => {
             callback.bind(thisArg)(value, key, this);
         });
     }
 
-    get(name: string) {
+    get(name: string): string {
         return this.headers[name] ?? null;
     }
 
@@ -65,19 +65,19 @@ export class AzleFetchHeaders {
         );
     }
 
-    has(name: string) {
+    has(name: string): boolean {
         return this.headers[name] !== undefined;
     }
 
-    keys() {
+    keys(): IterableIterator<string> {
         return Object.keys(this.headers)[Symbol.iterator]();
     }
 
-    set(name: string, value: string) {
+    set(name: string, value: string): void {
         this.headers[name] = value;
     }
 
-    values() {
+    values(): IterableIterator<string> {
         return Object.values(this.headers)[Symbol.iterator]();
     }
 }
diff --git a/src/lib/fetch/index.ts b/src/lib/fetch/index.ts
index 36ea2eab05..25217dcf5a 100644
--- a/src/lib/fetch/index.ts
+++ b/src/lib/fetch/index.ts
@@ -44,7 +44,7 @@ export function serialize(param: {
     return param as any;
 }
 
-function logWarnings(init?: RequestInit | undefined) {
+function logWarnings(init?: RequestInit | undefined): void {
     if (init === undefined) {
         return;
     }
@@ -90,7 +90,7 @@ function logWarnings(init?: RequestInit | undefined) {
     }
 }
 
-function logWarning(method: string) {
+function logWarning(method: string): void {
     console.warn(
         `azleFetch: init.${method} has no effect when using an identity as the Authorization header`
     );
diff --git a/src/lib/globals.ts b/src/lib/globals.ts
index 2454b396cc..5a1f8688dd 100644
--- a/src/lib/globals.ts
+++ b/src/lib/globals.ts
@@ -82,7 +82,7 @@ if (globalThis._azleInsideCanister) {
 
     globalThis.window = globalThis as any;
 
-    const log = (...args: any[]) => {
+    const log = (...args: any[]): void => {
         const jsonStringifiedArgs = args
             .map((arg) => {
                 if (arg instanceof Error) {
@@ -109,7 +109,7 @@ if (globalThis._azleInsideCanister) {
     (globalThis as any).setTimeout = (
         handler: TimerHandler,
         timeout?: number
-    ) => {
+    ): number => {
         if (timeout !== undefined && timeout !== 0) {
             console.warn(
                 `Azle Warning: setTimeout may not behave as expected with milliseconds above 0; called with ${timeout} milliseconds`,
@@ -164,7 +164,7 @@ if (globalThis._azleInsideCanister) {
         } as any
     };
 
-    globalThis.clearInterval = () => {}; // TODO should this throw an error or just not do anything? At least a warning would be good right?
+    globalThis.clearInterval = (): void => {}; // TODO should this throw an error or just not do anything? At least a warning would be good right?
 
     globalThis.global = globalThis;
     (globalThis as any).self = globalThis;
@@ -209,7 +209,7 @@ if (globalThis._azleInsideCanister) {
         configurable: true
     });
 
-    RegExp.prototype.exec = function (string) {
+    RegExp.prototype.exec = function (string): RegExpExecArray | null {
         const match = originalExec.call(this, string);
         if (match) {
             RegExp.leftContext = (string ?? '').substring(0, match.index);
@@ -221,7 +221,7 @@ if (globalThis._azleInsideCanister) {
     require('intl/locale-data/jsonp/en.js');
 }
 
-function stdioWrite(message: string) {
+function stdioWrite(message: string): void {
     // eslint-disable-next-line
     const ansiEscapeRegex = /\u001b\[.*?m/g;
     const newlineRegex = /\n/g;
diff --git a/src/lib/ic/call_raw.ts b/src/lib/ic/call_raw.ts
index 18e0a4b451..4b2536ce42 100644
--- a/src/lib/ic/call_raw.ts
+++ b/src/lib/ic/call_raw.ts
@@ -38,14 +38,16 @@ export function callRaw(
         // TODO perhaps we should be more robust
         // TODO for example, we can keep the time with these
         // TODO if they are over a certain amount old we can delete them
-        globalThis._azleResolveIds[globalResolveId] = (bytes: ArrayBuffer) => {
+        globalThis._azleResolveIds[globalResolveId] = (
+            bytes: ArrayBuffer
+        ): void => {
             resolve(new Uint8Array(bytes));
 
             delete globalThis._azleResolveIds[globalResolveId];
             delete globalThis._azleRejectIds[globalRejectId];
         };
 
-        globalThis._azleRejectIds[globalRejectId] = (error: any) => {
+        globalThis._azleRejectIds[globalRejectId] = (error: any): void => {
             reject(error);
 
             delete globalThis._azleResolveIds[globalResolveId];
diff --git a/src/lib/ic/call_raw_128.ts b/src/lib/ic/call_raw_128.ts
index 46f996beda..f6e42240fd 100644
--- a/src/lib/ic/call_raw_128.ts
+++ b/src/lib/ic/call_raw_128.ts
@@ -38,14 +38,16 @@ export function callRaw128(
         // TODO perhaps we should be more robust
         // TODO for example, we can keep the time with these
         // TODO if they are over a certain amount old we can delete them
-        globalThis._azleResolveIds[globalResolveId] = (bytes: ArrayBuffer) => {
+        globalThis._azleResolveIds[globalResolveId] = (
+            bytes: ArrayBuffer
+        ): void => {
             resolve(new Uint8Array(bytes));
 
             delete globalThis._azleResolveIds[globalResolveId];
             delete globalThis._azleRejectIds[globalRejectId];
         };
 
-        globalThis._azleRejectIds[globalRejectId] = (error: any) => {
+        globalThis._azleRejectIds[globalRejectId] = (error: any): void => {
             reject(error);
 
             delete globalThis._azleResolveIds[globalResolveId];
diff --git a/src/lib/ic/set_outgoing_http_options.ts b/src/lib/ic/set_outgoing_http_options.ts
index eddcf95ba5..52f5ca3fce 100644
--- a/src/lib/ic/set_outgoing_http_options.ts
+++ b/src/lib/ic/set_outgoing_http_options.ts
@@ -4,7 +4,7 @@ export function setOutgoingHttpOptions(options: {
     cycles?: bigint;
     transformMethodName?: string;
     transformContext?: Uint8Array;
-}) {
+}): void {
     globalThis._azleOutgoingHttpOptionsMaxResponseBytes =
         options.maxResponseBytes;
     globalThis._azleOutgoingHttpOptionsSubnetSize = options.subnetSize;
diff --git a/src/lib/ic/set_timer.ts b/src/lib/ic/set_timer.ts
index e9b9ef75ce..a53be1123e 100644
--- a/src/lib/ic/set_timer.ts
+++ b/src/lib/ic/set_timer.ts
@@ -26,7 +26,7 @@ export function setTimer(
 
     globalThis._azleIcTimers[timerId] = timerCallbackId;
 
-    globalThis._azleTimerCallbacks[timerCallbackId] = () => {
+    globalThis._azleTimerCallbacks[timerCallbackId] = (): void => {
         try {
             callback();
         } finally {
diff --git a/src/lib/stable/error.ts b/src/lib/stable/error.ts
index 8eaeb4d79e..14dcde2ddc 100644
--- a/src/lib/stable/error.ts
+++ b/src/lib/stable/error.ts
@@ -1,9 +1,9 @@
-import { ic } from '../ic';
+import { trap } from '.';
 
-export function handleUncaughtError(rawError: any) {
+export function handleUncaughtError(rawError: any): never {
     const error = rawError instanceof Error ? rawError : new Error(rawError);
 
     const azleError = `Uncaught ${error.name}: ${error.message}${error.stack}`;
 
-    ic.trap(azleError);
+    trap(azleError);
 }
diff --git a/src/lib/stable/execute_with_candid_serde.ts b/src/lib/stable/execute_with_candid_serde.ts
index 2d348ec93e..2e8b7a3c49 100644
--- a/src/lib/stable/execute_with_candid_serde.ts
+++ b/src/lib/stable/execute_with_candid_serde.ts
@@ -19,7 +19,7 @@ export function executeWithCandidSerde(
     paramIdls: IDL.Type[],
     returnIdl: IDL.Type | undefined,
     manual: boolean
-) {
+): void {
     const decodedArgs = IDL.decode(paramIdls, args[0]);
 
     const result = getResult(decodedArgs, callback);
diff --git a/src/lib/stable/guard.ts b/src/lib/stable/guard.ts
index 999b84758b..cd54672468 100644
--- a/src/lib/stable/guard.ts
+++ b/src/lib/stable/guard.ts
@@ -14,7 +14,7 @@ export function createGlobalGuard(
 
     const guardName = `_azleGuard_${guardedMethodName}`;
 
-    globalThis._azleGuardFunctions[guardName] = () => {
+    globalThis._azleGuardFunctions[guardName] = (): void => {
         try {
             guard();
         } catch (error) {
diff --git a/src/lib/stable/ic_apis/call.ts b/src/lib/stable/ic_apis/call.ts
index cec6074533..6f982d8bdb 100644
--- a/src/lib/stable/ic_apis/call.ts
+++ b/src/lib/stable/ic_apis/call.ts
@@ -29,7 +29,9 @@ export async function call(
         // TODO perhaps we should be more robust
         // TODO for example, we can keep the time with these
         // TODO if they are over a certain amount old we can delete them
-        globalThis._azleResolveIds[globalResolveId] = (result: ArrayBuffer) => {
+        globalThis._azleResolveIds[globalResolveId] = (
+            result: ArrayBuffer
+        ): void => {
             if (raw !== undefined) {
                 resolve(new Uint8Array(result));
             } else if (returnIdl === undefined) {
@@ -42,7 +44,7 @@ export async function call(
             delete globalThis._azleRejectIds[globalRejectId];
         };
 
-        globalThis._azleRejectIds[globalRejectId] = (error: any) => {
+        globalThis._azleRejectIds[globalRejectId] = (error: any): void => {
             reject(error);
 
             delete globalThis._azleResolveIds[globalResolveId];
diff --git a/src/lib/stable/ic_apis/set_outgoing_http_options.ts b/src/lib/stable/ic_apis/set_outgoing_http_options.ts
index eddcf95ba5..52f5ca3fce 100644
--- a/src/lib/stable/ic_apis/set_outgoing_http_options.ts
+++ b/src/lib/stable/ic_apis/set_outgoing_http_options.ts
@@ -4,7 +4,7 @@ export function setOutgoingHttpOptions(options: {
     cycles?: bigint;
     transformMethodName?: string;
     transformContext?: Uint8Array;
-}) {
+}): void {
     globalThis._azleOutgoingHttpOptionsMaxResponseBytes =
         options.maxResponseBytes;
     globalThis._azleOutgoingHttpOptionsSubnetSize = options.subnetSize;
diff --git a/src/lib/stable/ic_apis/set_timer.ts b/src/lib/stable/ic_apis/set_timer.ts
index e9b9ef75ce..a53be1123e 100644
--- a/src/lib/stable/ic_apis/set_timer.ts
+++ b/src/lib/stable/ic_apis/set_timer.ts
@@ -26,7 +26,7 @@ export function setTimer(
 
     globalThis._azleIcTimers[timerId] = timerCallbackId;
 
-    globalThis._azleTimerCallbacks[timerCallbackId] = () => {
+    globalThis._azleTimerCallbacks[timerCallbackId] = (): void => {
         try {
             callback();
         } finally {
diff --git a/src/lib/stable/init.ts b/src/lib/stable/init.ts
index f925135a46..300492afd4 100644
--- a/src/lib/stable/init.ts
+++ b/src/lib/stable/init.ts
@@ -10,7 +10,7 @@ export function init(paramIdls: IDL.Type[]): MethodDecorator {
     ): TypedPropertyDescriptor<T> | void => {
         const originalMethod = (descriptor.value as any).bind(target);
 
-        const methodCallback = (...args: any[]) => {
+        const methodCallback = (...args: any[]): void => {
             executeWithCandidSerde(
                 'init',
                 args,
diff --git a/src/lib/stable/mark_experimental.ts b/src/lib/stable/mark_experimental.ts
index 3dfc532f0e..1a8979c0fd 100644
--- a/src/lib/stable/mark_experimental.ts
+++ b/src/lib/stable/mark_experimental.ts
@@ -1,4 +1,4 @@
-export function markExperimental() {
+export function markExperimental(): void {
     if (process.env.AZLE_EXPERIMENTAL !== 'true') {
         throw new Error(`Azle: the experimental flag must be set`);
     }
diff --git a/src/lib/stable/post_upgrade.ts b/src/lib/stable/post_upgrade.ts
index a721b6b42f..2b85187d75 100644
--- a/src/lib/stable/post_upgrade.ts
+++ b/src/lib/stable/post_upgrade.ts
@@ -10,7 +10,7 @@ export function postUpgrade(paramIdls: IDL.Type[]): MethodDecorator {
     ): TypedPropertyDescriptor<T> | void => {
         const originalMethod = (descriptor.value as any).bind(target);
 
-        const methodCallback = (...args: any[]) => {
+        const methodCallback = (...args: any[]): void => {
             executeWithCandidSerde(
                 'postUpgrade',
                 args,
diff --git a/src/lib/stable/query.ts b/src/lib/stable/query.ts
index d3a86f57b3..d26c448784 100644
--- a/src/lib/stable/query.ts
+++ b/src/lib/stable/query.ts
@@ -19,7 +19,7 @@ export function query(
     ): TypedPropertyDescriptor<T> | void => {
         const originalMethod = (descriptor.value as any).bind(target);
 
-        const methodCallback = (...args: any[]) => {
+        const methodCallback = (...args: any[]): void => {
             executeWithCandidSerde(
                 'query',
                 args,
diff --git a/src/lib/stable/update.ts b/src/lib/stable/update.ts
index f95f8ecf86..405e3a3dad 100644
--- a/src/lib/stable/update.ts
+++ b/src/lib/stable/update.ts
@@ -18,7 +18,7 @@ export function update(
     ): TypedPropertyDescriptor<T> | void => {
         const originalMethod = (descriptor.value as any).bind(target);
 
-        const methodCallback = (...args: any[]) => {
+        const methodCallback = (...args: any[]): void => {
             executeWithCandidSerde(
                 'update',
                 args,
diff --git a/src/lib/stable_structures/stable_json.ts b/src/lib/stable_structures/stable_json.ts
index 7a6893f922..cb0d71cec0 100644
--- a/src/lib/stable_structures/stable_json.ts
+++ b/src/lib/stable_structures/stable_json.ts
@@ -6,7 +6,7 @@ export function StableJson(options?: {
     reviver?: typeof jsonReviver;
 }): Serializable {
     return {
-        toBytes(data: any) {
+        toBytes(data: any): Uint8Array {
             const result = JSON.stringify(
                 data,
                 options?.replacer ?? jsonReplacer
@@ -14,7 +14,7 @@ export function StableJson(options?: {
 
             return Uint8Array.from(Buffer.from(result));
         },
-        fromBytes(bytes: Uint8Array) {
+        fromBytes(bytes: Uint8Array): any {
             return JSON.parse(
                 Buffer.from(bytes).toString(),
                 options?.reviver ?? jsonReviver
diff --git a/src/lib/system_types/result.ts b/src/lib/system_types/result.ts
index 03cf6657fa..ec88cb8f87 100644
--- a/src/lib/system_types/result.ts
+++ b/src/lib/system_types/result.ts
@@ -13,7 +13,7 @@ export class AzleResult<T extends CandidType, K extends CandidType> {
     Ok: T;
     Err: K;
 
-    getIdl(parents: Parent[]) {
+    getIdl(parents: Parent[]): IDL.VariantClass {
         return IDL.Variant({
             Ok: toIdl(this.Ok, parents),
             Err: toIdl(this.Err, parents)
@@ -24,7 +24,7 @@ export class AzleResult<T extends CandidType, K extends CandidType> {
 export function Result<Ok extends CandidType, Err extends CandidType>(
     ok: Ok,
     err: Err
-) {
+): AzleResult<Ok, Err> {
     return new AzleResult<Ok, Err>(ok, err);
 }
 
@@ -40,19 +40,19 @@ export type Result<Ok, Err> = RequireExactlyOne<{
 //
 // eslint-disable-next-line @typescript-eslint/no-namespace
 export namespace Result {
-    export function Ok<T>(value: T) {
+    export function Ok<T>(value: T): Result<T, any> {
         return { Ok: value };
     }
 
-    export function Err<T>(value: T) {
+    export function Err<T>(value: T): Result<any, T> {
         return { Err: value };
     }
 }
 
-export function Ok<T>(value: T) {
+export function Ok<T>(value: T): Result<T, any> {
     return { Ok: value };
 }
 
-export function Err<T>(value: T) {
+export function Err<T>(value: T): Result<any, T> {
     return { Err: value };
 }