[Haskell-cafe] Re: Differences in optimisiation with interactive and compiled mo

Am Donnerstag, 8. Dezember 2005 19:17 schrieb Branimir Maksimovic:

From: Henning Thielemann

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To: Branimir Maksimovic CC: haskell-cafe@haskell.org Subject: Re: [Haskell-cafe] Differences in optimisiation with interactive and compiled mode Date: Thu, 8 Dec 2005 18:38:45 +0100 (MET)

On Thu, 8 Dec 2005, Branimir Maksimovic wrote:

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program performs search replace on a String

http://www.haskell.org/pipermail/haskell-cafe/2005-April/009692.html

This is nice and ellegant but example search replace program runs more then 50% faster with my implementation.

Greetings, Bane.

That's probably because Lemmih's is polymorphic. Yesterday evening, I cooked up my own version srchrep :: String -> String -> String -> String srchrep "" rp st = st -- or should it rather be cycle rp ? srchrep sr rp st | sr == rp = st srchrep sr@(c:cs) rep inp = process inp where process str = case start "" str of Nothing -> str Just (pre, post) -> reverse pre ++ rep ++ process post start _ "" = Nothing start pre (s:st) | s == c = cont pre [s] cs st | otherwise = start (s:pre) st cont pre _ "" st = Just (pre, st) cont _ _ _ "" = Nothing cont pre fnd (p:pat) (s:st) | s == p && s == c = abort pre (p:fnd) pat st `mplus` cont (fnd ++ pre) [s] cs st | s == p = cont pre (p:fnd) pat st | s == c = cont (fnd ++ pre) [s] cs st | otherwise = start (s:fnd ++ pre) st abort pre _ "" st = Just (pre, st) abort pre fnd (p:pat) (s:st) | s == p = abort pre (s:fnd) pat st abort _ _ _ _ = Nothing and today I compared the versions, with Lemmih's type specialized to String -> ... -> String. Then Lemmih's is a bit faster than mine (a bit slower, if compiled for profiling) which is still a bit faster than yours (and, profiling, yours is significantly slower than the others. Cheers, Daniel