Lucid: Intention Specification

Lucid is a programming language that allows both dynamic and static typing, immutable data structures, atom-like state management, modern concurrency mechanisms, and seamless integration of S-expressions with C-like syntax. It transpiles to PHP, enabling execution within the PHP ecosystem. (I am not sure if guaranteeing interop is worth the effort.)

Core Features

1. Data Structures

   • Maps: Key-value collections supporting heterogeneous types.

     let user = {:name "Alice",
                 :age 30,
                 :preferences ["reading", "gaming"]}

   • Vectors: Ordered, indexable collections with mixed types.

     let numbers = [1, 2, 3, "apple", "mango"]

2. Immutability and Persistence

   • Immutable by Default: Data structures are immutable unless explicitly mutable.
   • Persistent Structures: Modifications generate new instances efficiently without full duplication.

     let updatedUser = user.assoc(:age, 31)

3. Typing System

   • Dynamic Typing: Define functions and variables without type annotations.

     func greet(name) {
         return "Hello, " + name
     }

   • Static Typing: Optional type annotations for parameters and return types, enforced at compile-time.

     func add(a: Int, b: Int) -> Int {
         return a + b
     }

   • Gradual Typing: Mix dynamic and static types within the same codebase.

4. Functional Programming

   • Higher-Order Functions: Functions that accept or return other functions.
   • Pure Functions: Functions without side effects, ensuring predictability.
   • Built-In Functions: Includes assoc, dissoc, conj, update, get for data manipulation.

     let newColors = colors.conj("yellow")

5. Concurrency Model

   • Atom: Manages shared, mutable state safely.

     let counter = Atom({:count 0})
     counter.swap { data in
        data.assoc(:count, data["count"] + 1)
     }

   • Thread Safety: Immutable data structures prevent race conditions.
   • Structured Concurrency: Supports asynchronous operations and task management.

6. Macro System

   • Metaprogramming: Enables code generation and transformation.

     macro unless(condition, block) {
         return if (!condition) { block }
     }
     
     unless(user.isLoggedIn) {
         redirectToLogin()
     }

7. REPL-Driven Development

   • Interactive Environment: Facilitates real-time code evaluation, debugging, and testing.
   • Immediate Feedback: Supports iterative development and experimentation.

8. Interoperability

   • Database Integration: Native support for relational databases.

     let db = Database.connect("relational.db")
     let users = db.query("SELECT * FROM users")

   • External Libraries: Compatible with existing systems and tools, enabling seamless integration.

9. S-Expressions Integration

   • Native Support: S-expressions are integral to Lucid's syntax.

     (define (factorial n)
         (if (<= n 1)
             1
             (* n (factorial (- n 1)))))

   • Interoperability with C-like Syntax: Allows mixing S-expressions with standard code.

     let greeting = "Hello, World!"
     
     (define (printGreeting)
         (print greeting))
     
     func main() {
         printGreeting()
     }

   • Seamless Parsing: Compiler/interpreter handles mixed S-expression and C-like Syntax without errors.

10. Transpilation to PHP

    • Compilation Process: Transpiles Lucid source code into PHP code for execution within the PHP runtime.
    • PHP Integration: Leverages PHP's ecosystem, including libraries and frameworks.
    • Interoperability: Allows use of PHP functions and classes within Lucid programs.
    • Performance Optimization: Transpilation includes optimizations to ensure efficient PHP output.
    • Error Handling: Maps Lucid's type and runtime errors to corresponding PHP exceptions.
    • Deployment: Generated PHP code deploys on standard PHP servers.

    Example Transpilation:

    • Lucid Code:

      func factorial(n: Int) -> Int {
          if (n <= 1) {
              return 1
          } else {
              return n * factorial(n - 1)
          }
      }
      
      func main() {
          let result = factorial(5)
          print(result)  // Outputs: 120
      }
      
      main()

    • Transpiled PHP Code:

      <?php
      function factorial(int $n): int {
          if ($n <= 1) {
              return 1;
          } else {
              return $n * factorial($n - 1);
          }
      }
      
      function main() {
          $result = factorial(5);
          echo $result;  // Outputs: 120
      }
      
      main();
      ?>

Syntax and Usage

1. Defining Data Structures

   • HashMap:

     let product = {:id 101, :name "Laptop", :price 999.99, :tags ["electronics", "computers"]}

   • Vector:

     let colors = ["red", "green", "blue", 42]

2. Function Definitions

   • Dynamic Typing:

     func concatenate(a, b) {
         return a + b
     }

   • Static Typing:

     func multiply(a: Int, b: Int) -> Int {
         return a * b
     }

3. Data Manipulation

   • Add Key-Value Pair:

     let updatedProduct = product.assoc(:stock, 50)

   • Remove Key:

     let simplifiedProduct = product.dissoc(:tags)

   • Append to Vector:

     let newColors = colors.conj("yellow")

4. Concurrency Operations

   • Atomic State Management:

     let sharedState = Atom({:balance 1000})
     
     func deposit(amount: Int) {
         sharedState.swap { data in data.assoc(:balance, data["balance"] + amount) }
     }
     
     func withdraw(amount: Int) {
         sharedState.swap { data in data.assoc(:balance, data["balance"] - amount) }
     }

5. Macro Usage

   • Conditional Macro:

     macro unless(condition, block) {
         return if (!condition) { block }
     }
     
     unless(user.isLoggedIn) {
         redirectToLogin()
     }

6. S-Expressions Usage

   • Defining Functions with S-Expressions:

     (define (square x)
         (* x x))
     
     let result = square(5)
     print(result)  // Outputs: 25

   • Mixing with C-like Syntax:

     let message = "Factorial of 5 is: "
     
     (define (factorial n)
         (if (<= n 1)
             1
             (* n (factorial (- n 1)))))
     
     func main() {
         let fact = factorial(5)
         print(message + fact)
     }