Hello Simon, Friday, May 30, 2008, 5:30:25 PM, you wrote:
may be i don't understand something. isn't it better to do automatic SAT and inline results for every recursive function marked as INLINE? it's how i want to work - just mark with INLINE speed-critical funcs. manual checking that they are recursive and doing appropriate transformation is too hard for me :) and, btw, how about adding warnings about functions marked as INLINE which was not actually inlined due to some reasons - may be very helpful for optimizing programs without going into studying Core output > Others have explained this nicely. But there's a real tension > here. The fast version comes from a combination of (a) the static > argument transformation, so you get the first version above, and (b) > bodily inlining the entire function, so that at *each call site* you > get a locally-recursive function where 'f' is known. That's ok for > small functions, but not so good for big ones. Furthermore, the > code duplication is only worthwhile if the specialisation is truly > useful. For example, would it be better to write append like this > (++) xs ys = letrec app [] = ys > app (x:xs) = x : app xs > in app xs > and inline that at every call of (++)? Probably not. > So that is why GHC does not automate this transformation. If you > know that's what you want, write a local recursion, and use an INLINE pragma. > If someone felt like summarising this thread on the Haskell > performance-advice wiki that would be great. > http://haskell.org/haskellwiki/Performance > Meanwhile, I'll clarify in the user manual that recursive functions are not > inlined. > Simon > _______________________________________________ > Glasgow-haskell-users mailing list > Glasgow-haskell-users@haskell.org > http://www.haskell.org/mailman/listinfo/glasgow-haskell-users -- Best regards, Bulat mailto:[EMAIL PROTECTED] _______________________________________________ Glasgow-haskell-users mailing list Glasgow-haskell-users@haskell.org http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
