From 178c5d54d533c4fd594e2e5fe9d2b8c570838058 Mon Sep 17 00:00:00 2001
From: Remo <remo>
Date: Tue, 21 Apr 2020 17:59:33 +0200
Subject: [PATCH] Integrate stack in the nix-shell environment

---
 nix/README.md | 4 +++-
 shell.nix     | 8 ++++++++
 2 files changed, 11 insertions(+), 1 deletion(-)

diff --git a/nix/README.md b/nix/README.md
index 84f84df9a..820c99f5d 100644
--- a/nix/README.md
+++ b/nix/README.md
@@ -38,7 +38,9 @@ nix-shell
 
 ```
 
-Within `nix-shell`, you can run Cabal commands as usual.
+Within `nix-shell`, you can run Cabal commands as usual. You can also run
+stack with the `--nix` option, which causes stack to pick up the non-Haskell
+dependencies from the same pinned Nixpkgs version that the Nix builds use.
 
 ## Tour
 
diff --git a/shell.nix b/shell.nix
index 69bca8533..c5989dd03 100644
--- a/shell.nix
+++ b/shell.nix
@@ -4,9 +4,17 @@ pkgs.lib.overrideDerivation env (
     buildInputs =
       base.buildInputs ++ [
         pkgs.cabal-install
+        pkgs.stack
         pkgs.cabal2nix
         pkgs.postgresql
         nixpkgsUpgrade
       ];
+
+    shellHook =
+      ''
+        # Set our pinned version of Nixpkgs in the NIX_PATH so that
+        # `stack --nix` also uses that version.
+        NIX_PATH="nixpkgs=${pinnedPkgs}"
+      '';
   }
 )