From 3a763b91963ef747b188e7062d7a02119d2ef6d3 Mon Sep 17 00:00:00 2001
From: Shea Levy <shea@shealevy.com>
Date: Wed, 10 Jan 2018 12:08:36 -0500
Subject: [PATCH] haskellLib: Add shellAware function

---
 pkgs/development/haskell-modules/lib.nix | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/pkgs/development/haskell-modules/lib.nix b/pkgs/development/haskell-modules/lib.nix
index 6a724130d25..da4e9c6777b 100644
--- a/pkgs/development/haskell-modules/lib.nix
+++ b/pkgs/development/haskell-modules/lib.nix
@@ -154,6 +154,10 @@ rec {
     (p.override { mkDerivation = extractBuildInputs p.compiler;
                 }).haskellBuildInputs;
 
+  # Under normal evaluation, simply return the original package. Under
+  # nix-shell evaluation, return a nix-shell optimized environment.
+  shellAware = p: if lib.inNixShell then p.env else p;
+
   ghcInfo = ghc:
     rec { isCross = (ghc.cross or null) != null;
           isGhcjs = ghc.isGhcjs or false;