4 files changed, 98 insertions, 0 deletions
diff --git a/third_party/overlays/haskell/.skip-subtree b/third_party/overlays/haskell/.skip-subtree
new file mode 100644
index 0000000000..2a528eaa8a
--- /dev/null
+++ b/third_party/overlays/haskell/.skip-subtree
@@ -0,0 +1 @@
+extra-pkgs need to be callPackage-ed
diff --git a/third_party/overlays/haskell/default.nix b/third_party/overlays/haskell/default.nix
new file mode 100644
index 0000000000..0ed0196a28
--- /dev/null
+++ b/third_party/overlays/haskell/default.nix
@@ -0,0 +1,31 @@
+# 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
+  };
+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 { };
+        }
+      );
+    };
+  };
+}
diff --git a/third_party/overlays/haskell/extra-pkgs/random-fu-0.2.nix b/third_party/overlays/haskell/extra-pkgs/random-fu-0.2.nix
new file mode 100644
index 0000000000..1626eca7be
--- /dev/null
+++ b/third_party/overlays/haskell/extra-pkgs/random-fu-0.2.nix
@@ -0,0 +1,41 @@
+{ mkDerivation
+, base
+, erf
+, lib
+, math-functions
+, monad-loops
+, mtl
+, random
+, random-shuffle
+, random-source
+, rvar
+, syb
+, template-haskell
+, transformers
+, vector
+}:
+mkDerivation {
+  pname = "random-fu";
+  version = "0.2.7.7";
+  sha256 = "8466bcfb5290bdc30a571c91e1eb526c419ea9773bc118996778b516cfc665ca";
+  revision = "1";
+  editedCabalFile = "16nhymfriygqr2by9v72vdzv93v6vhd9z07pgaji4zvv66jikv82";
+  libraryHaskellDepends = [
+    base
+    erf
+    math-functions
+    monad-loops
+    mtl
+    random
+    random-shuffle
+    random-source
+    rvar
+    syb
+    template-haskell
+    transformers
+    vector
+  ];
+  homepage = "https://github.com/mokus0/random-fu";
+  description = "Random number generation";
+  license = lib.licenses.publicDomain;
+}
diff --git a/third_party/overlays/haskell/extra-pkgs/rvar-0.2.nix b/third_party/overlays/haskell/extra-pkgs/rvar-0.2.nix
new file mode 100644
index 0000000000..c00f5a1a8d
--- /dev/null
+++ b/third_party/overlays/haskell/extra-pkgs/rvar-0.2.nix
@@ -0,0 +1,25 @@
+{ mkDerivation
+, base
+, lib
+, MonadPrompt
+, mtl
+, random-source
+, transformers
+}:
+mkDerivation {
+  pname = "rvar";
+  version = "0.2.0.6";
+  sha256 = "01e18875ffde43f9591a8acd9f60c9c51704a026e51c1a6797faecd1c7ae8cd3";
+  revision = "1";
+  editedCabalFile = "1jn9ivlj3k65n8d9sfsp882m5lvni1ah79mk0cvkz91pgywvkiyq";
+  libraryHaskellDepends = [
+    base
+    MonadPrompt
+    mtl
+    random-source
+    transformers
+  ];
+  homepage = "https://github.com/mokus0/random-fu";
+  description = "Random Variables";
+  license = lib.licenses.publicDomain;
+}