[Haskell-cafe] Stream fusion

Hello, While re-reading RealWorldHaskell, chapter 25, I saw that -- unlike I believed -- loop fusion wasn't activated by default under GHC for lists (but that module Data.List.Stream from package stream-fusion could provide it). Is that still the case? If not, then are there some cases of list processing where loop fusion would be a bad thing? (Ergo cases where you should stick to Prelude/Data.List functions and not use Data.List.Stream implementation) Thanks.