Haskell : Setup flake env.

Readme.md

@@ -41,4 +41,4 @@ I'll merge them together later, when I finish re-visiting.
 
 ### Shiny new stuff!
 
-- [ ] Haskell.
+- [ ] [Haskell](haskell).

haskell/flake.nix

@@ -0,0 +1,27 @@
+{
+	description = "Haskell dev env.";
+
+	inputs = {
+		nixpkgs.url = "github:nixos/nixpkgs/nixos-unstable";
+	};
+
+	outputs = { self, nixpkgs } @inputs: let
+		system = "x86_64-linux";
+		lib    = nixpkgs.lib;
+		pkgs   = nixpkgs.legacyPackages.${system};
+	in {
+		devShells.${system} = {
+			default = pkgs.mkShell rec {
+				nativeBuildInputs = with pkgs; [
+					haskell-language-server
+					stylish-haskell
+					ghc
+					haskellPackages.lsp
+				];
+				buildInputs = with pkgs; [
+
+				];
+			};
+		};
+	};
+}