# Defines an overlay for overriding Haskell packages, for example to
# avoid breakage currently present in nixpkgs or to modify package
# versions.

{ lib, ... }:

self: super: # overlay parameters for the nixpkgs overlay

let
  overrides = hsSelf: hsSuper: with self.haskell.lib.compose; {
    # No overrides for the default package set necessary at the moment
    # TODO(sterni): upstreamable?
    generic-arbitrary = appendPatch
      (self.fetchpatch {
        name = "generic-arbitrary-no-negative-resize.patch";
        url = "https://github.com/typeable/generic-arbitrary/commit/c13d119d8ad0d43860ecdb93b357b0239e366a6c.patch";
        sha256 = "1jgbd2jn575icqw9nfdzh57nacm3pn8n53ka52129pnfjqfzyhsi";
      })
      hsSuper.generic-arbitrary;
  };
in
{
  haskellPackages = super.haskellPackages.override {
    inherit overrides;
  };

  haskell = lib.recursiveUpdate super.haskell {
    packages.ghc8107 = super.haskell.packages.ghc8107.override {
      overrides = lib.composeExtensions overrides (
        hsSelf: hsSuper: with self.haskell.lib.compose; {
          # TODO(sterni): TODO(grfn): patch xanthous to work with random-fu 0.3.*,
          # so we can use GHC 9.0.2 and benefit from upstream binary cache.
          random-fu = hsSelf.callPackage ./extra-pkgs/random-fu-0.2.nix { };
          rvar = hsSelf.callPackage ./extra-pkgs/rvar-0.2.nix { };

          # TODO(sterni): upstream this
          universe-base = addBuildDepend hsSelf.OneTuple hsSuper.universe-base;
        }
      );
    };
  };
}