refactor(gemma): Move Gemma source into monorepo stucture

services/gemma/default.nix

@@ -0,0 +1,49 @@
+with import <nixpkgs> {};
+
+stdenv.mkDerivation rec {
+  name = "gemma";
+
+  src = ./.;
+
+  buildInputs = with lispPackages; [
+    sbcl
+    quicklisp
+    hunchentoot
+    cl-json
+    local-time
+    elmPackages.elm
+    pkgconfig
+  ];
+
+  # The build phase has three distinct things it needs to do:
+  #
+  # 1. "Compile" the Elm source into something useful to browsers.
+  #
+  # 2. Configure the Lisp part of the application to serve the compiled Elm
+  #
+  # 3. Build (and don't strip!) an executable out of the Lisp backend.
+  buildPhase = ''
+    mkdir -p $out/share/gemma $out/bin
+    mkdir .home && export HOME="$PWD/.home"
+
+    # Build Elm
+    cd frontend
+    elm-make --yes Main.elm --output $out/share/gemma/index.html
+
+    # Build Lisp
+    cd $src
+    quicklisp init
+    env GEMMA_BIN_TARGET=$out/bin/gemma sbcl --load build.lisp
+  '';
+
+  installPhase = "true";
+
+  # Stripping an SBCL executable removes the application, which is unfortunate.
+  dontStrip = true;
+
+  meta = with stdenv.lib; {
+    description = "Tool for tracking recurring tasks";
+    homepage    = "https://github.com/tazjin/gemma";
+    license     = licenses.gpl3;
+  };
+}