Install GHC via Nix

Author: sestrella

devenv.lock

@@ -89,11 +89,27 @@
         "type": "github"
       }
     },
+    "nixpkgs-unstable": {
+      "locked": {
+        "lastModified": 1742923925,
+        "owner": "nixos",
+        "repo": "nixpkgs",
+        "rev": "25d1b84f5c90632a623c48d83a2faf156451e6b1",
+        "type": "github"
+      },
+      "original": {
+        "owner": "nixos",
+        "ref": "nixpkgs-unstable",
+        "repo": "nixpkgs",
+        "type": "github"
+      }
+    },
     "root": {
       "inputs": {
         "devenv": "devenv",
         "git-hooks": "git-hooks",
         "nixpkgs": "nixpkgs",
+        "nixpkgs-unstable": "nixpkgs-unstable",
         "pre-commit-hooks": [
           "git-hooks"
         ]

devenv.nix

@@ -1,8 +1,16 @@
-{ pkgs, lib, config, inputs, ... }:
+{ pkgs, inputs, ... }:
 
+let
+  pkgs-unstable = import inputs.nixpkgs-unstable {
+    system = pkgs.stdenv.system;
+  };
+in
 {
-
   packages = [
-    pkgs.stack
+    pkgs-unstable.haskell.compiler.ghc984
   ];
+
+  scripts.stack.exec = ''
+    ${pkgs.stack}/bin/stack --system-ghc "$@"
+  '';
 }

devenv.yaml

@@ -2,14 +2,5 @@
 inputs:
   nixpkgs:
     url: github:cachix/devenv-nixpkgs/rolling
-
-# If you're using non-OSS software, you can set allowUnfree to true.
-# allowUnfree: true
-
-# If you're willing to use a package that's vulnerable
-# permittedInsecurePackages:
-#  - "openssl-1.1.1w"
-
-# If you have more than one devenv you can merge them
-#imports:
-# - ./backend
+  nixpkgs-unstable:
+    url: github:nixos/nixpkgs/nixpkgs-unstable