{ mkDerivation, base, containers, fetchurl, hashable
, template-haskell, unordered-containers
}:
mkDerivation {
  pname = "once";
  version = "0.2";
  src = fetchurl {
    url = "http://example.org/";
    sha256 = "abc";
  };
  libraryHaskellDepends = [
    base containers hashable template-haskell unordered-containers
  ];
  homepage = "https://anonscm.debian.org/cgit/users/kaction-guest/haskell-once.git";
  description = "memoization for IO actions and functions";
  license = stdenv.lib.licenses.gpl3;
}