-zipEqual [] [] = []
-zipEqual (a:as) (b:bs) = (a,b) : zipEqual as bs
-zipEqual as bs = panic "zipEqual: unequal lists"
-
-zipWithEqual z (a:as) (b:bs) = z a b : zipWithEqual z as bs
-zipWithEqual _ [] [] = []
-zipWithEqual _ _ _ = panic "zipWithEqual: unequal lists"
-
-zipWith3Equal z (a:as) (b:bs) (c:cs)
- = z a b c : zipWith3Equal z as bs cs
-zipWith3Equal _ [] [] [] = []
-zipWith3Equal _ _ _ _ = panic "zipWith3Equal: unequal lists"
-
-zipWith4Equal z (a:as) (b:bs) (c:cs) (d:ds)
- = z a b c d : zipWith4Equal z as bs cs ds
-zipWith4Equal _ [] [] [] [] = []
-zipWith4Equal _ _ _ _ _ = panic "zipWith4Equal: unequal lists"
+zipEqual msg [] [] = []
+zipEqual msg (a:as) (b:bs) = (a,b) : zipEqual msg as bs
+zipEqual msg as bs = panic ("zipEqual: unequal lists:"++msg)
+
+zipWithEqual msg z (a:as) (b:bs)= z a b : zipWithEqual msg z as bs
+zipWithEqual msg _ [] [] = []
+zipWithEqual msg _ _ _ = panic ("zipWithEqual: unequal lists:"++msg)
+
+zipWith3Equal msg z (a:as) (b:bs) (c:cs)
+ = z a b c : zipWith3Equal msg z as bs cs
+zipWith3Equal msg _ [] [] [] = []
+zipWith3Equal msg _ _ _ _ = panic ("zipWith3Equal: unequal lists:"++msg)
+
+zipWith4Equal msg z (a:as) (b:bs) (c:cs) (d:ds)
+ = z a b c d : zipWith4Equal msg z as bs cs ds
+zipWith4Equal msg _ [] [] [] [] = []
+zipWith4Equal msg _ _ _ _ _ = panic ("zipWith4Equal: unequal lists:"++msg)