#9369: Data.List.unfoldr does not fuse and is not inlined. -------------------------------------+------------------------------------- Reporter: dfeuer | Owner: Type: bug | Status: closed Priority: normal | Milestone: 7.8.4 Component: | Version: 7.8.3 libraries/base | Keywords: Resolution: fixed | 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: Phab:D198 | -------------------------------------+------------------------------------- Comment (by dfeuer): Replying to [comment:9 nomeata]:
Small followup: According to http://ghcspeed- nomeata.rhcloud.com/changes/?rev=78209d70596dcbfcb11ad1de1c961ab8479e531e&exe=2&env=nomeata%27s%20buildbot no significant changes in performance can be observed.
The reason for this is very simple: not a single one of those benchmarks uses `unfoldr` anywhere. The only benchmarks in the `nofib` tree that use it are the `fibon` ones, which are not run by default: {{{ [dfeuer@lemur nofib]$ find . -name "*hs" -exec grep unfoldr \{\} \; -print split n xs = unfoldr (g n) xs ./fibon/Hackage/Crypto/Codec/Text/Raw.hs blocks = map (fromOctets 256) (unfoldr h $ concat $ unfoldr g s) concat $ unfoldr g s where ./fibon/Hackage/Crypto/Codec/Encryption/Padding.hs import Data.List(unfoldr) unfoldr f $ md5s $ Str $ map (chr . fromIntegral) xs ./fibon/Hackage/Crypto/Data/Digest/MD5.hs unfoldr g unfoldr g ./fibon/Hackage/Crypto/Data/Digest/SHA1.hs padding x = unfoldr block $ paddingHelper x 0 (0::Int) (0::Integer) ./fibon/Hackage/Crypto/Data/Digest/SHA2.hs import Data.List (unfoldr) unroll = unfoldr step ./fibon/Hackage/Gf/src/runtime/haskell/Data/Binary.hs }}} -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/9369#comment:10 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler