#8668: SPECIALIZE silently fails to apply -------------------------------------+---------------------------------- Reporter: crockeea | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.6.2 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: x86_64 (amd64) Type of failure: None/Unknown | Difficulty: Unknown Test Case: | Blocked By: Blocking: | Related Tickets: -------------------------------------+---------------------------------- Comment (by crockeea): Replying to [comment:4 simonpj]:
Incidentally, if you want GHC to auto-specialise an '''imported''' function, to types that may not even be in scope in the defining module, you should mark that function as `INLINABLE`
I have been playing around with this some more, and found something interesting. As I mentioned, despite the fact that I have everything marked `INLINABLE`, GHC was *not* auto-specializing `plusFastCyc`. However, if I partially apply the call to `plusFastCyc` in Main to `iterate (plusFastCyc y) ...` instead of `iterate (\x -> plusFastCyc y x) ...`, GHC *does* automatically specialize the call to `plusFastCyc`. However, the code is still slow because `(+)` is still not specialized. I might expect (+) to be specialized for two reasons 1. It is called at the top level in Main.hs in the `foldl`. 2. The docs say that *when* there is an explicit pragma, specialization is transitive. I could hope that auto-specialization is also transitive. Is this the case? Is the problem of GHC specializing the partially applied function but not the fully applied version related to ticket:8099? -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/8668#comment:19 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler