On Thu, Oct 27, 2011 at 10:03 AM, Edward Z. Yang
I'd like to remark that the situation with keys is not /quite/ comparable. Even if we don't need to look at the key for inserting into an empty map, it will get forced anyway because IntMaps are spine-strict (in particular, they are strict in their keys.)
I'm not quite sure if I follow. Here's Data.IntMap.insert: insert :: Key -> a -> IntMap a -> IntMap a insert k x t = k `seq` case t of Bin p m l r | nomatch k p m -> join k (Tip k x) p t | zero k m -> Bin p m (insert k x l) r | otherwise -> Bin p m l (insert k x r) Tip ky _ | k==ky -> Tip k x | otherwise -> join k (Tip k x) ky t Nil -> Tip k x Without the explicit `seq` insert undefined 1 Nil terminates but with the `seq` it's _|_. Are you saying it will eventually get force if someone e.g. does a lookup after the insert? -- Johan