{ stdenv, lib, fetchurl, registryDat }:

ver: deps:
let
  cmds = lib.mapAttrsToList
    (name: info:
      let
        pkg = stdenv.mkDerivation {
          name = lib.replaceStrings [ "/" ] [ "-" ] name + "-${info.version}";

          src = fetchurl {
            url = "https://github.com/${name}/archive/${info.version}.tar.gz";
            meta.homepage = "https://github.com/${name}/";
            inherit (info) sha256;
          };

          dontConfigure = true;
          dontBuild = true;

          installPhase = ''
            mkdir -p $out
            cp -r * $out
          '';
        };
      in
      ''
        mkdir -p .elm/${ver}/packages/${name}
        cp -R ${pkg} .elm/${ver}/packages/${name}/${info.version}
      '')
    deps;
in
(lib.concatStrings cmds) + ''
  mkdir -p .elm/${ver}/packages;
  cp ${registryDat} .elm/${ver}/packages/registry.dat;
  chmod -R +w .elm
''