Add nix derivation

.gitignore

@@ -1,3 +1,4 @@
 .stack-work/
 .vscode/
 *.swp
+result

package.yaml

@@ -32,7 +32,7 @@ library:
   source-dirs: src
 
 executables:
-  utoy-exe:
+  utoy:
     main:                Main.hs
     source-dirs:         app
     ghc-options:

utoy.cabal

@@ -36,7 +36,7 @@ library
     , text
   default-language: Haskell2010
 
-executable utoy-exe
+executable utoy
   main-is: Main.hs
   hs-source-dirs:
       app

utoy.nix

@@ -0,0 +1,20 @@
+let
+  pkgs = import ./nix/pkgs.nix {};
+  settings = import ./nix/settings.nix;
+  haskellDeps = import ./nix/haskell-deps.nix;
+
+  haskellPackages = pkgs.haskell.packages."${settings.ghc}";
+
+  utoy =
+    { mkDerivation }:
+    mkDerivation {
+      version = "0.1.0.0";
+      pname = "utoy";
+      license = pkgs.lib.licenses.mit;
+      src = ./.;
+
+      libraryHaskellDepends = haskellDeps haskellPackages;
+    };
+in
+  pkgs.haskell.lib.justStaticExecutables
+    (haskellPackages.callPackage utoy {})