{ mkDerivation, base, fetchurl }:
mkDerivation {
  pname = "cassette";
  version = "0.1.0";
  src = fetchurl {
    url = "http://example.org/";
    sha256 = "abc";
  };
  libraryHaskellDepends = [ base ];
  description = "A combinator library for simultaneously defining parsers and pretty printers";
  license = stdenv.lib.licenses.bsd3;
}