#9356: scanl does not participate in stream fusion -------------------------------------+------------------------------------- Reporter: dfeuer | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.8.2 Keywords: | Operating System: Architecture: Unknown/Multiple | Unknown/Multiple Difficulty: Unknown | Type of failure: Runtime Blocked By: | performance bug Related Tickets: | Test Case: | Blocking: | Differential Revisions: -------------------------------------+------------------------------------- nomeata came up with a fusing version of a strict `scanl'` in a comment on #9345. It's not entirely clear to me whether that's entirely safe, but a non-strict version of it for `scanl` would be, as both a good producer and good consumer, presumably made efficient using the same sorts of magic used in HEAD for `foldl`. The strict `scanl'` is obviously safe to write as a good consumer; only the production side remains to be proved. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/9356 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler