[add IsEmpty as superclass, get rid of 'null' method
John Meacham <john@repetae.net>**20060409081618] hunk ./Util/SetLike.hs 29
-class (Monoid s,HasSize s) => SetLike s where
+class (Monoid s,HasSize s,IsEmpty s) => SetLike s where
hunk ./Util/SetLike.hs 34
-    null :: s -> Bool
hunk ./Util/SetLike.hs 35
-    disjoint x y = Util.SetLike.null (x `intersection` y)
+    disjoint x y = isEmpty (x `intersection` y)
hunk ./Util/SetLike.hs 69
-    null = IS.null
hunk ./Util/SetLike.hs 86
-    null = S.null
hunk ./Util/SetLike.hs 102
-    null = IM.null
hunk ./Util/SetLike.hs 114
-    null = M.null
hunk ./Util/SetLike.hs 133
+    mkeys :: m -> [k]
+    mfilter :: (v -> Bool) -> m -> m
hunk ./Util/SetLike.hs 143
+    mkeys = IM.keys
+    mfilter = IM.filter
hunk ./Util/SetLike.hs 151
+    mkeys = M.keys
+    mfilter = M.filter
hunk ./Util/SetLike.hs 158
-    deriving(Typeable,Monoid,SetLike,HasSize,Eq,Ord)
+    deriving(Typeable,Monoid,SetLike,HasSize,Eq,Ord,IsEmpty)