#10260: last uses too much space with optimizations disabled -------------------------------------+------------------------------------- Reporter: rwbarton | Owner: nomeata Type: bug | Status: patch Priority: normal | Milestone: Component: Core Libraries | Version: 7.10.1 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Type of failure: Runtime | Unknown/Multiple performance bug | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Revisions: Phab:D844 -------------------------------------+------------------------------------- Comment (by nomeata): `INLINEABLE` does not work; probably because the unfolding looks too large. But `INLINE` seems to work. So with this patch {{{ -last = foldl (\_ x -> x) (errorEmptyList "last") +last xs = foldl (\_ x -> x) lastError xs +{-# INLINE last #-} +lastError = errorEmptyList "last" }}} we have * that `GHC.List.last` is used without `-O`, with the desired memory behaviour, * with `-O`, `last` gets inlined and fusion can happen. (`lastError` pulled out to not copy that wherever `last` is used). -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/10260#comment:7 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler