#15131: Speed up certain Foldable NonEmpty methods -------------------------------------+------------------------------------- Reporter: dfeuer | Owner: (none) Type: bug | Status: patch Priority: normal | Milestone: 8.6.1 Component: Core Libraries | Version: 8.2.2 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Type of failure: Runtime | Unknown/Multiple performance bug | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Phab:D4677 Wiki Page: | -------------------------------------+------------------------------------- Comment (by YitzGale): Replying to [comment:3 dfeuer]:
Yours has to hold on to the "and then add one" while calculating the length of the list.
Are you sure GHC doesn't inline the {{{+1}}}? In any case, this is slightly better: {{{#!hs length (_ :| as) = List.foldl' (\c _ -> c+1) 1 as }}}
Same goes for `max` and `min`.
Yes, and also for {{{product}}} and {{{sum}}}, but I did that purposely. I want the semantics to be the same as for {{{List}}}, which is a bit weird because it uses {{{foldl}}}. And I don't want to hard-code a copy of the {{{foldl}}} here. I want it to be fixed automatically if we every get around to fixing it for List. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/15131#comment:4 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler