fix: actually add haskell

templates/haskell/flake.nix

@@ -0,0 +1,33 @@
+{
+  description = "Cool Haskell Project with an unknown purpose";
+  inputs = {
+    nixpkgs.url = "github:NixOS/nixpkgs/nixos-24.05";
+    treefmt.url = "github:numtide/treefmt-nix";
+  };
+  outputs =
+    inputs@{ nixpkgs, ... }:
+    let
+      lib = nixpkgs.lib;
+      systems = [ "x86_64-linux" ];
+      forAllSystems =
+        f:
+        lib.genAttrs systems (
+          system:
+          f {
+            pkgs = import nixpkgs {
+              inherit system;
+            };
+          }
+        );
+      treefmtEval = forAllSystems ({ pkgs }: inputs.treefmt.lib.evalModule pkgs ./flake/treefmt.nix);
+    in
+    {
+      packages = forAllSystems ({ pkgs }: {
+        cool-haskell-project = pkgs.callPackage ./flake/package.nix {};
+      });
+      devShells = forAllSystems ({ pkgs }: {
+        default = pkgs.callPackage ./flake/shell.nix {};
+      });
+      formatter = forAllSystems ({ pkgs }: treefmtEval.${pkgs.system}.config.build.wrapper);
+    };
+}