#8173: GHC uses nub -------------------------------------+------------------------------------- Reporter: nh2 | Owner: leroux Type: bug | Status: closed Priority: normal | Milestone: Component: Compiler | Version: 7.6.3 Resolution: wontfix | Keywords: Operating System: Unknown/Multiple | Architecture: Unknown/Multiple Type of failure: Compile-time | Difficulty: Moderate (less performance bug | than a day) Test Case: | Blocked By: Blocking: | Related Tickets: -------------------------------------+------------------------------------- Changes (by leroux): * status: new => closed * resolution: => wontfix Comment: Full nofib analysis of head, ordNub, and ordNub-cases (each ran twice): https://gist.github.com/leroux/6750216 I took certain measures to make sure the nofib benchmarks would return "truer" results. I think you'll find the results much more reliable now. According to the results, sadly the 5% performance gain in compile time was complete bogus. Sorry. =( Snippet from https://gist.github.com/leroux/6750216#file-full-ordnub- analysis-L2880-L3467 (compile times): {{{ Compile Times ------------------------------------------------------------------------------- Program head-0 head-1 ordNub-0 ordNub-1 ordNub-cases-0 ordNub-cases-1 ------------------------------------------------------------------------------- -1 s.d. ----- -1.6% -1.6% -1.7% -1.7% -1.7% +1 s.d. ----- +1.9% +2.1% +1.6% +2.0% +1.7% Average ----- +0.1% +0.2% -0.0% +0.1% -0.0% }}} I'm closing this ticket now since there is no obvious improvement from replacing `nub` with `ordNub`. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/8173#comment:12 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler