add Data.Set.notMember and Data.Map.notMember

[ghc-base.git] / Data / Map.hs

diff --git a/Data/Map.hs b/Data/Map.hs
index 24d8d2d..7124cd3 100644 (file)
--- a/Data/Map.hs
+++ b/Data/Map.hs
@@ -44,6 +44,7 @@ module Data.Map  (
             , null
             , size
             , member
+            , notMember
             , lookup
             , findWithDefault
             
@@ -272,6 +273,10 @@ member k m
       Nothing -> False
       Just x  -> True
 
+-- | /O(log n)/. Is the key not a member of the map?
+notMember :: Ord k => k -> Map k a -> Bool
+notMember k m = not $ Data.Map.member k m
+
 -- | /O(log n)/. Find the value at a key.
 -- Calls 'error' when the element can not be found.
 find :: Ord k => k -> Map k a -> a