#9356: scanl does not participate in stream fusion -------------------------------------+------------------------------------- Reporter: dfeuer | Owner: Type: bug | Status: patch Priority: normal | Milestone: Component: Compiler | Version: 7.8.3 Resolution: | 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: | -------------------------------------+------------------------------------- Comment (by dfeuer): There is some kind of bad interaction that makes `sum . concat . inits $ [1..10000]` explode (use tons of RAM) when `inits` is written using a `scanl'` similar to this `scanl`. If this is affected, it may not be ready to go after all. I can fix the problem by breaking the pipeline between `concat` and `inits`; there also isn't a problem if I drop the `sum`. If I use `foldl' (+) 0` instead of `sum`, then it doesn't explode anymore, but it still allocates excessively and runs slowly. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/9356#comment:4 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler