1 files changed, 48 insertions, 0 deletions
diff --git a/third_party/overlays/haskell/default.nix b/third_party/overlays/haskell/default.nix
new file mode 100644
index 000000000000..8c4871fb084a
--- /dev/null
+++ b/third_party/overlays/haskell/default.nix
@@ -0,0 +1,48 @@
+# 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;
+    };
+  };
+
+  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 { };
+      };
+    };
+  };
+}