first haskell template

haskell/flake.nix

@@ -0,0 +1,33 @@
+{
+  description = "A very basic Haskell flake";
+  inputs = {
+    nixpkgs.url = "github:NixOS/nixpkgs/nixpkgs-unstable";
+  };
+
+
+  outputs = { self, nixpkgs, ...}: 
+  let
+    supportedSystems = [ "x86_64-linux" "x86_64-darwin" "aarch64-linux" "aarch64-darwin" ];
+    forAllSystems = nixpkgs.lib.genAttrs supportedSystems;
+    pkgs = forAllSystems (system: nixpkgs.legacyPackages.${system});
+    stack-wrapped = pkgs.symlinkJoin {
+      name = "stack"; # will be available as the usual `stack` in terminal
+      paths = [ pkgs.stack ];
+      buildInputs = [ pkgs.makeWrapper ];
+      postBuild = ''
+          wrapProgram $out/bin/stack \
+              --add-flags "\
+              --no-nix \
+              --system-ghc \
+              --no-install-ghc \
+            "
+    '';
+    };
+  in
+  {
+    devShells = forAllSystems (system: {
+      default = pkgs.${system}.callPackage ./shell.nix {};
+      LD_LIBRARY_PATH = pkgs.lib.makeLibraryPath self.default.buildInputs;
+    });
+  };
+}