Re: [GHC] #9781: Make list monad operations fuse

#9781: Make list monad operations fuse -------------------------------------+------------------------------------- Reporter: dfeuer | Owner: dfeuer Type: task | Status: patch Priority: normal | Milestone: 7.10.1 Component: Core | Version: 7.9 Libraries | Keywords: Resolution: | Architecture: Unknown/Multiple Operating System: | Difficulty: Unknown Unknown/Multiple | Blocked By: Type of failure: Runtime | Related Tickets: performance bug | Test Case: | Blocking: | Differential Revisions: Phab:D455 | -------------------------------------+------------------------------------- Comment (by Herbert Valerio Riedel ): In [changeset:"4923cea56345060faaf77e4c475eac6aa3c77506/ghc"]: {{{ #!CommitTicketReference repository="ghc" revision="4923cea56345060faaf77e4c475eac6aa3c77506" Define list monad operations using comprehensions Define list monad operations using list comprehensions. Code using monad operations with lists did not fuse fully. Writing list code with `do` notation or `(>>=)` and `(>>)` operations could allocate more than equivalent code using list comprehensions. Define `mapM` directly, instead of using `sequence` and `map`. This leads to substantially less allocation in `cryptarithm2`. Addresses #9781 Reviewed By: ekmett, nomeata Differential Revision: https://phabricator.haskell.org/D455 }}} -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/9781#comment:4 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler