From 2e8e2be67ac02bd5c466ce2608cca05136ce9dfd Mon Sep 17 00:00:00 2001
From: Luca Bruno <lethalman88@gmail.com>
Date: Tue, 8 Jul 2014 11:27:31 +0200
Subject: [PATCH] Evaluate NArgSet to NVArgSet

---
 Nix/Eval.hs | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/Nix/Eval.hs b/Nix/Eval.hs
index 1faad2d..738fbdc 100644
--- a/Nix/Eval.hs
+++ b/Nix/Eval.hs
@@ -4,7 +4,7 @@ import           Control.Applicative
 import           Control.Arrow
 import           Control.Monad hiding (mapM)
 import qualified Data.Map as Map
-import           Data.Traversable
+import           Data.Traversable as T
 import           Nix.Types
 import           Prelude hiding (mapM)
 
@@ -40,7 +40,7 @@ evalExpr = cata phi
     --     Fix . NVConstant . NStr . T.concat
     --         <$> mapM (fmap valueText . ($ env)) l
 
-    phi (NArgSet _xs) = error "Cannot evaluate an argument set"
+    phi (NArgSet s) = \env -> Fix . NVArgSet <$> mapM (T.sequence . fmap ($ env)) s
 
     phi (NSet _b xs)   = \env ->
         Fix . NVSet . Map.fromList