Hello-world haskell package.

nix/pkgs/uterm/default.nix

@@ -0,0 +1,37 @@
+{ pkgs ? import ../../nixpkgs.nix }:
+
+let
+
+  compiler    = "default";
+  doBenchmark = false;
+
+  run-hpack =
+    "${pkgs.haskellPackages.hpack}/bin/hpack";
+
+  f = { mkDerivation, stdenv,
+        base, classy-prelude, lens, hpack, megaparsec }:
+      mkDerivation {
+        pname = "uterm";
+        version = "0.1.0.0";
+        src = ../../../pkg/uterm;
+        isLibrary = false;
+        isExecutable = true;
+        executableHaskellDepends = [
+          base classy-prelude lens hpack megaparsec
+        ];
+        license = stdenv.lib.licenses.lgpl3;
+        preConfigure = ''
+          ${run-hpack}
+        '';
+      };
+
+  haskellPackages = if compiler == "default"
+                       then pkgs.haskellPackages
+                       else pkgs.haskell.packages.${compiler};
+
+  variant = if doBenchmark then pkgs.haskell.lib.doBenchmark else pkgs.lib.id;
+  drv     = variant (haskellPackages.callPackage f {});
+
+in
+
+  if pkgs.lib.inNixShell then drv.env else drv

pkg/uterm/Main.hs

@@ -0,0 +1,9 @@
+module Main where
+
+import ClassyPrelude
+import Control.Lens
+
+--------------------------------------------------------------------------------
+
+main :: IO ()
+main = "Hello World" & putStrLn

pkg/uterm/package.dhall

@@ -0,0 +1,27 @@
+{ name =
+    "uterm"
+, version =
+    "0.1.0"
+, license =
+    "AGPL-3.0-only"
+, default-extensions =
+    [ "OverloadedStrings"
+    , "TypeApplications"
+    , "UnicodeSyntax"
+    , "FlexibleContexts"
+    , "TemplateHaskell"
+    , "QuasiQuotes"
+    , "LambdaCase"
+    , "NoImplicitPrelude"
+    , "ScopedTypeVariables"
+    , "DeriveAnyClass"
+    , "DeriveGeneric"
+    ]
+, dependencies =
+    [ "base"
+    , "classy-prelude"
+    , "lens"
+    ]
+, executables =
+    { pomo = { main = "Main.hs" } }
+}

pkg/uterm/shell.nix

@@ -0,0 +1 @@
+import ../../nix/pkgs/uterm/default.nix