From 5a7c295cb1ff3edc97d8053061ef67d7dc36aa2a Mon Sep 17 00:00:00 2001
From: Yuriy Taraday <yuriy.taraday@tweag.io>
Date: Fri, 29 Sep 2023 15:37:25 +0200
Subject: [PATCH] Move checks to project.ncl

It's unclear if we need to implement runCommand ourselves, it's quite
simple to achieve necesary result with plaing NixpkgsPkg override.

Introduce NixEnvironmentVariable contract to handle all possible things
than might end up in `env`.

Part of https://github.com/nickel-lang/organist/issues/58.
---
 flake.nix        | 25 -------------------------
 lib/builders.ncl |  4 ++--
 project.ncl      | 40 ++++++++++++++++++++++++++++++++++++++++
 3 files changed, 42 insertions(+), 27 deletions(-)

diff --git a/flake.nix b/flake.nix
index 62bc8a09..95d693f5 100644
--- a/flake.nix
+++ b/flake.nix
@@ -100,31 +100,6 @@
               program = pkgs.lib.getExe testScript;
             };
           };
-
-        checks.alejandra = pkgs.runCommand "check-alejandra" {} ''
-          ${pkgs.lib.getExe pkgs.alejandra} --check ${self}
-          touch $out
-        '';
-
-        checks.nickel-format =
-          pkgs.runCommand "check-nickel-format" {
-            buildInputs = [
-              inputs.nickel.packages.${system}.nickel-lang-cli
-            ];
-          } ''
-            cd ${self}
-            failed=""
-            for f in $(find . -name future -prune -or -name '*.ncl' -print); do
-              if ! diff -u "$f" <(nickel format -f "$f"); then
-                failed="$failed $f"
-              fi
-            done
-            if [ "$failed" != "" ]; then
-              echo "Following files need to be formatted: $failed"
-              exit 1
-            fi
-            touch $out
-          '';
       }
     );
 }
diff --git a/lib/builders.ncl b/lib/builders.ncl
index ce90c208..ed2f231f 100644
--- a/lib/builders.ncl
+++ b/lib/builders.ncl
@@ -1,4 +1,4 @@
-let { NickelDerivation, Derivation, NixString, .. } = import "contracts.ncl" in
+let { NickelDerivation, Derivation, NixString, NixEnvironmentVariable, .. } = import "contracts.ncl" in
 
 let lib = import "lib.ncl" in
 
@@ -56,7 +56,7 @@ in
         },
         structured_env = {},
         env = {
-          stdenv = lib.import_nix "nixpkgs#stdenv"
+          stdenv | default = lib.import_nix "nixpkgs#stdenv",
         },
         nix_drv = env & structured_env,
       }
diff --git a/project.ncl b/project.ncl
index 3616fae8..4a43707c 100644
--- a/project.ncl
+++ b/project.ncl
@@ -15,5 +15,45 @@ let import_nix = organist.lib.import_nix in
         nls = import_nix "nickel#lsp-nls",
       },
     },
+
+  flake.checks
+    | {
+      _ | {
+        version
+        = "",
+        env.stdenv
+        = import_nix "nixpkgs#stdenvNoCC",
+        ..
+      }
+    }
+    | { _ | organist.builders.NixpkgsPkg }
+    = {
+      alejandra = {
+        name = "check-alejandra",
+        env.buildCommand = nix-s%"
+          %{import_nix "nixpkgs#alejandra"}/bin/alejandra --check %{import_nix "self"}
+          touch $out
+        "%,
+      },
+
+      nickel-format = {
+        name = "check-nickel-format",
+        env.buildInputs.nickel = import_nix "nickel#nickel-lang-cli",
+        env.buildCommand = nix-s%"
+          cd %{import_nix "self"}
+          failed=""
+          for f in $(find . -name future -prune -or -name '*.ncl' -print); do
+            if ! diff -u "$f" <(nickel format -f "$f"); then
+              failed="$failed $f"
+            fi
+          done
+          if [ "$failed" != "" ]; then
+            echo "Following files need to be formatted: $failed"
+            exit 1
+          fi
+          touch $out
+        "%,
+      },
+    },
 }
   | organist.contracts.OrganistExpression