#9434: GHC.List.reverse does not fuse -------------------------------------+------------------------------------- Reporter: dfeuer | Owner: Type: bug | Status: infoneeded Priority: normal | Milestone: Component: | Version: 7.9 libraries/base | Keywords: Resolution: | Architecture: Unknown/Multiple Operating System: | Difficulty: Easy (less than 1 Unknown/Multiple | hour) Type of failure: Runtime | Blocked By: performance bug | Related Tickets: Test Case: | Blocking: | Differential Revisions: | -------------------------------------+------------------------------------- Changes (by nomeata): * status: patch => infoneeded Comment: Is this understanding correct: `reverse` is made a good consumer, and additionally, it is a good producer when immediately consumed by `map`. You might make the rules simpler by using `mapReverseFB revId` instead of `revFB`: No need to have both `mapMapReverse` and `mapReverse` then. There is quite a bit of logic in this patch. Would you mind adding test cases for this, so that this behaviour is not accidentally broken in the future? -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/9434#comment:14 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler