From 91a9e302fd485ad07fa8f3bf8967babcc556d042 Mon Sep 17 00:00:00 2001
From: Sridhar Ratnakumar <srid@srid.ca>
Date: Sun, 5 Dec 2021 16:46:03 -0500
Subject: [PATCH] Make 'nix develop' work on m1 mac

---
 flake.nix | 37 +++++++++++++++++++++++++++----------
 1 file changed, 27 insertions(+), 10 deletions(-)

diff --git a/flake.nix b/flake.nix
index 3e93186..f7a3613 100644
--- a/flake.nix
+++ b/flake.nix
@@ -14,6 +14,21 @@
         overlays = [ ];
         pkgs =
           import nixpkgs { inherit system overlays; config.allowBroken = true; };
+        # https://github.com/NixOS/nixpkgs/issues/140774#issuecomment-976899227
+        m1MacHsBuildTools =
+          pkgs.haskellPackages.override {
+            overrides = self: super:
+              let
+                workaround140774 = hpkg: with pkgs.haskell.lib;
+                  overrideCabal hpkg (drv: {
+                    enableSeparateBinOutput = false;
+                  });
+              in
+              {
+                ghcid = workaround140774 super.ghcid;
+                ormolu = workaround140774 super.ormolu;
+              };
+          };
         project = returnShellEnv:
           pkgs.haskellPackages.developPackage {
             inherit returnShellEnv;
@@ -25,16 +40,18 @@
               # cf. https://tek.brick.do/K3VXJd8mEKO7
             };
             modifier = drv:
-              pkgs.haskell.lib.addBuildTools drv (with pkgs.haskellPackages;
-              [
-                # Specify your build/dev dependencies here. 
-                cabal-fmt
-                cabal-install
-                ghcid
-                haskell-language-server
-                ormolu
-                pkgs.nixpkgs-fmt
-              ]);
+              pkgs.haskell.lib.addBuildTools drv
+                (with (if system == "aarch64-darwin"
+                then m1MacHsBuildTools
+                else pkgs.haskellPackages); [
+                  # Specify your build/dev dependencies here. 
+                  cabal-fmt
+                  cabal-install
+                  ghcid
+                  haskell-language-server
+                  ormolu
+                  pkgs.nixpkgs-fmt
+                ]);
           };
       in
       {