#7994: Make foldl into a good consumer -------------------------------------+------------------------------------ Reporter: simonpj | Owner: Type: bug | Status: closed Priority: normal | Milestone: Component: Compiler | Version: 7.6.3 Resolution: fixed | Keywords: Operating System: Unknown/Multiple | Architecture: Unknown/Multiple Type of failure: None/Unknown | Difficulty: Unknown Test Case: | Blocked By: Blocking: | Related Tickets: -------------------------------------+------------------------------------ Comment (by nomeata): JFTR: I’m currently working on a presentation and short paper on this, and did some measurements, and found that while making `foldl` a good consumer has a nice effect on allocations (`-4.1%`, the overall effect on the runtime is negligible). Effect of Call Arity (with the original foldl): {{{ min mean max Allocations -1.3% -0.1% 0.0% Runtime -10.8% -0.9% +2.0% }}} Effect of Call Arity + defining foldl with foldr: {{{ min mean max Allocations -74.5% -4.1% 0.0% Runtime -10.4% -0.9% +1.7% }}} (Wishful thinking: Maybe there are real-world programs that would benefit more noticeably, but they are just not included in nofib) -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/7994#comment:20 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler