Hi all, for my work on the containers I need to settle some questions about strictness. Thank you very much for your opinions. Discussion ends: 23. July 2010. 1) Strictness of keys and values in the datatype. Currently we have the following strictness flags in the datatypes: - IntMap: !key value - IntSet: !key - Map: !key value - Set: key I vote for changing Set to store keys also strict. Storing values as nonstrict probably makes sense. 2) Strictness of keys and values in the method definitions. The IntMap.lookup (lookup k t = ... seq k ...) evaluates the given key even if it is not needed (when searching empty tree). Some methods are more carefull. I vote for all IntMap, IntSet, Map and Set methods that are given a key value (insert, delete, member, ...) to be strict in the keys. This a) would be consistent with 1) b) would be a bit more efficient (~5% in the IntMap.lookup case) 3) Strict folds Currently there are no strict folds. I vote for adding strict folds (fold', foldWithKey' when appropriate) to all Map, Set, IntMap, IntSet. Cheers, Milan Straka PS: I will be unavailable and not reading mail till 19. July 2010.