Hi, In GHC: Prelude> maximum [] *** Exception: Prelude.maximum: empty list In Hugs: Prelude> maximum [] Program error: pattern match failure: foldl1 (Ord_max instOrd_v29) [] Obviously this is because foldl1 is used to define maximum, but it would be nice if the equation maximum [] = error "pattern match failure in maximum" was issued, otherwise people might end up grepping for foldl1 which doesn't ever occur in their code. Thanks Neil