#14001: Inlining does not work between modules -------------------------------------+------------------------------------- Reporter: danilo2 | Owner: (none) Type: bug | Status: new Priority: high | Milestone: Component: Compiler | Version: 8.0.2 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by bgamari): Regarding comment:10: In general GHC can only evaluate things which it can prove will eventually be forced by the program. Consequently if you have, {{{#!hs (.) :: (b -> c) -> (a -> b) -> a -> c (.) f g = \x -> f (g x) h = f . g }}} The performance characteristics of `h` will naturally depend upon the strictness characteristics of `f` and `g`. If both are strict in their first argument then it would be safe to first force `h`'s argument, as you do in your strict composition operator. However, if either are lazy then changing the strictness of `(.)` will change the semantics of the program, potentially resulting in an incorrectly bottom program.
Thus I believe we should consider this bug and should expect from GHC to automatically optimize usages of `(.)` in strict code.
Perhaps, but what do you consider to be "strict code"? -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/14001#comment:12 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler