{ gf-core
, breakpointHook
, fetchFromGitHub
, compiler ? "ghc98"
, haskell
, pgf2-haskell
, gf-pgf
}:

let
  src = fetchFromGitHub {
    owner = "GrammaticalFramework";
    repo = "gftest";
    rev = "ef7c99143d84a29fb28bbc464f661566d44a6130";
    hash = "sha256-t/LaG5+bdv7f0URcn/aFx6nUIvxSSEbpWeZS92/Gbog=";
  };
  hpkgs = haskell.packages.${compiler}.extend (final: prev: {
    # PGF2, the Haskell bindings to the C library.
    pgf2 = pgf2-haskell.override { inherit compiler; };
  });
  pkg = hpkgs.callCabal2nix "gftest" src {};
in pkg.overrideAttrs (final: prev: {
  nativeBuildInputs = (prev.nativeBuildInputs or []) ++ [
    breakpointHook
  ];
})