From 699cf456cbd85f54201d113b23104da41d5f856d Mon Sep 17 00:00:00 2001
From: bjorn <bjorn@bringert.net>
Date: Fri, 30 May 2008 15:38:35 +0000
Subject: [PATCH] Changes lookConcrFlag to return Maybe.

---
 src-3.0/PGF/Macros.hs | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/src-3.0/PGF/Macros.hs b/src-3.0/PGF/Macros.hs
index 01ab1bb6b..3577ed23a 100644
--- a/src-3.0/PGF/Macros.hs
+++ b/src-3.0/PGF/Macros.hs
@@ -51,9 +51,12 @@ lookAbsFlag :: PGF -> CId -> String
 lookAbsFlag pgf f = 
   lookMap "?" f (aflags (abstract pgf))
 
-lookCncFlag :: PGF -> CId -> CId -> String
-lookCncFlag pgf lang f = 
-  lookMap "?" f $ cflags $ lookMap (error "no lang") lang $ concretes pgf
+lookConcr :: PGF -> CId -> Concr
+lookConcr pgf cnc = 
+    lookMap (error $ "Missing concrete syntax: " ++ prCId cnc) cnc $ concretes pgf
+
+lookConcrFlag :: PGF -> CId -> CId -> Maybe String
+lookConcrFlag pgf lang f = Map.lookup f $ cflags $ lookConcr pgf lang
 
 functionsToCat :: PGF -> CId -> [(CId,Type)]
 functionsToCat pgf cat =