# 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
  haskellLib = self.haskell.lib.compose;
  dhall-source = subdir: pkg:
    haskellLib.overrideSrc
      {
        src = "${super.fetchFromGitHub {
          owner = "Profpatsch";
          repo = "dhall-haskell";
          # https://github.com/dhall-lang/dhall-haskell/pull/2426
          rev = "5e3a407d8ac826597d935d8398825a0ca73fc4e9";
          sha256 = "005plj6kgxlkm9npaq07kmsgmiqk50dpwb9li9w1ly4aj1zgfjnd";
        }}/${subdir}";
      }
      (haskellLib.overrideCabal { patches = [ ]; } pkg);


in
{
  haskellPackages = super.haskellPackages.override {
    overrides = hsSelf: hsSuper: {
      # TODO: this is to fix a bug in dhall-nix
      dhall = dhall-source "dhall" hsSuper.dhall;
      dhall-nix = dhall-source "dhall-nix" hsSuper.dhall-nix;

      pa-prelude = hsSelf.callPackage ./extra-pkgs/pa-prelude-0.1.0.0.nix { };
      pa-error-tree = hsSelf.callPackage ./extra-pkgs/pa-error-tree-0.1.0.0.nix { };
      pa-field-parser = hsSelf.callPackage ./extra-pkgs/pa-field-parser-0.1.0.1.nix { };
      pa-label = hsSelf.callPackage ./extra-pkgs/pa-label-0.1.0.1.nix { };
    };
  };

  haskell = lib.recursiveUpdate super.haskell {
    packages.ghc8107 = super.haskell.packages.ghc8107.override {
      overrides = hsSelf: hsSuper: {
        # 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(grfn): port to brick 1.4 (EventM gains an additional type argument in 1.0)
        brick = hsSelf.callPackage ./extra-pkgs/brick-0.73.nix { };
      };
    };
  };
}