{ mkDerivation, base, constraints, fetchurl }:
mkDerivation {
  pname = "poly-arity";
  version = "0.1.0";
  src = fetchurl {
    url = "http://example.org/";
    sha256 = "abc";
  };
  libraryHaskellDepends = [ base constraints ];
  description = "Tools for working with functions of undetermined arity";
  license = stdenv.lib.licenses.bsd3;
}