From 292a8892a091905500105be931d8ddb4bc3cd68c Mon Sep 17 00:00:00 2001
From: Mathieu Boespflug <m@tweag.io>
Date: Sun, 5 Jun 2016 00:19:06 +0200
Subject: [PATCH 1/4] haskell.lib.buildStackProject: allow passing in a custom
 GHC version.

Previously, the user could only compile using the default version of
GHC in Nixpkgs. Now this can be changed by setting the `ghc` attribute
appropriately.
---
 pkgs/development/haskell-modules/generic-stack-builder.nix | 1 +
 1 file changed, 1 insertion(+)

diff --git a/pkgs/development/haskell-modules/generic-stack-builder.nix b/pkgs/development/haskell-modules/generic-stack-builder.nix
index 94999ed8c45a..caada71632d5 100644
--- a/pkgs/development/haskell-modules/generic-stack-builder.nix
+++ b/pkgs/development/haskell-modules/generic-stack-builder.nix
@@ -5,6 +5,7 @@ with stdenv.lib;
 { buildInputs ? []
 , extraArgs ? []
 , LD_LIBRARY_PATH ? ""
+, ghc ? ghc
 , ...
 }@args:
 

From e6aa4e0ccb6b169eaa4ff5ff28f332e078c018b4 Mon Sep 17 00:00:00 2001
From: Mathieu Boespflug <m@tweag.io>
Date: Sun, 5 Jun 2016 00:30:37 +0200
Subject: [PATCH 2/4] doc: Document how to set custom GHC version in
 haskell.lib.buildStackProject.

---
 doc/languages-frameworks/haskell.md | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/doc/languages-frameworks/haskell.md b/doc/languages-frameworks/haskell.md
index e066ad110bec..cdabcbe0379d 100644
--- a/doc/languages-frameworks/haskell.md
+++ b/doc/languages-frameworks/haskell.md
@@ -378,6 +378,23 @@ special options turned on:
 	  buildInputs = [ R zeromq zlib ];
     }
 
+You can select a particular GHC version to compile with by setting the
+`ghc` attribute as an argument to `buildStackProject`. Better yet, let
+Stack choose what GHC version it wants based on the snapshot specified
+in `stack.yaml` (only works with Stack >= 1.1.3):
+
+    {nixpkgs ? import <nixpkgs> { }, ghc ? nixpkgs.ghc}
+
+    with nixpkgs;
+
+    let R = pkgs.R.override { enableStrictBarrier = true; };
+    in
+	haskell.lib.buildStackProject {
+      name = "HaskellR";
+	  buildInputs = [ R zeromq zlib ];
+	  inherit ghc;
+    }
+
 [stack-nix-doc]: http://docs.haskellstack.org/en/stable/nix_integration.html
 
 ### How to create ad hoc environments for `nix-shell`

From 70bc97b731c74beb95b3cb95939ed6b9ea02b9b8 Mon Sep 17 00:00:00 2001
From: Mathieu Boespflug <m@tweag.io>
Date: Mon, 13 Jun 2016 00:53:20 +0200
Subject: [PATCH 3/4] haskell.lib.buildStackProject: fix treatment of
 LD_LIBRARY_PATH.

Don't make LD_LIBRARY_PATH pick up cwd when original string is empty,
due to colon terminated search path.
---
 pkgs/development/haskell-modules/generic-stack-builder.nix | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/pkgs/development/haskell-modules/generic-stack-builder.nix b/pkgs/development/haskell-modules/generic-stack-builder.nix
index caada71632d5..07421b1d14f8 100644
--- a/pkgs/development/haskell-modules/generic-stack-builder.nix
+++ b/pkgs/development/haskell-modules/generic-stack-builder.nix
@@ -4,7 +4,7 @@ with stdenv.lib;
 
 { buildInputs ? []
 , extraArgs ? []
-, LD_LIBRARY_PATH ? ""
+, LD_LIBRARY_PATH ? []
 , ghc ? ghc
 , ...
 }@args:
@@ -23,7 +23,7 @@ stdenv.mkDerivation (args // {
     extraArgs;
 
   # XXX: workaround for https://ghc.haskell.org/trac/ghc/ticket/11042.
-  LD_LIBRARY_PATH = "${makeLibraryPath buildInputs}:${LD_LIBRARY_PATH}";
+  LD_LIBRARY_PATH = makeLibraryPath (LD_LIBRARY_PATH ++ buildInputs);
 
   preferLocalBuild = true;
 

From 3adf86eed6fcfc1baaba46e3052863876f0a91f7 Mon Sep 17 00:00:00 2001
From: Mathieu Boespflug <m@tweag.io>
Date: Mon, 13 Jun 2016 11:42:50 +0200
Subject: [PATCH 4/4] doc(haskell): Remove pesky tabs in code snippets.

---
 doc/languages-frameworks/haskell.md | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/doc/languages-frameworks/haskell.md b/doc/languages-frameworks/haskell.md
index cdabcbe0379d..2ddec0d9aba4 100644
--- a/doc/languages-frameworks/haskell.md
+++ b/doc/languages-frameworks/haskell.md
@@ -389,10 +389,10 @@ in `stack.yaml` (only works with Stack >= 1.1.3):
 
     let R = pkgs.R.override { enableStrictBarrier = true; };
     in
-	haskell.lib.buildStackProject {
+    haskell.lib.buildStackProject {
       name = "HaskellR";
-	  buildInputs = [ R zeromq zlib ];
-	  inherit ghc;
+      buildInputs = [ R zeromq zlib ];
+      inherit ghc;
     }
 
 [stack-nix-doc]: http://docs.haskellstack.org/en/stable/nix_integration.html