- make sure type t always come first
- Map.map, Map.fold, ... never pass the key to the callback while Map.mapi, Map.foldi, ... do
- removed the ~key and ~data labels, I find them useless and annoying
- Set.elements --> Set.to_list
- Map.bindings --> Map.to_list
- Map.of_alist --> Map.of_list
- added Ordering.t for comparison functions
- renamed Inl/Inr to Left/Right. The latter seems clearer
- moved List.longest to String.longest
- added a Pp module with a nicer API than Format