From 2a931e52e1c8b93d03df89d1e78011dc4d112a74 Mon Sep 17 00:00:00 2001
From: John Wiegley <johnw@newartisans.com>
Date: Fri, 4 Jul 2014 02:06:27 -0500
Subject: [PATCH] Add a stub in the evaluator for operators

---
 Nix/Eval.hs | 1 +
 1 file changed, 1 insertion(+)

diff --git a/Nix/Eval.hs b/Nix/Eval.hs
index 0ad7c46..1faad2d 100644
--- a/Nix/Eval.hs
+++ b/Nix/Eval.hs
@@ -31,6 +31,7 @@ evalExpr = cata phi
   where
     phi :: NExprF (NValue -> IO NValue) -> NValue -> IO NValue
     phi (NConstant x) = const $ return $ Fix $ NVConstant x
+    phi (NOper _x) = error "Operators are not yet defined"
 
     phi (NList l)     = \env ->
         Fix . NVList <$> mapM ($ env) l