Re: [Haskell-cafe] Re: Write Haskell as fast as C.

ketil:

Andrew Coppin writes:

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I'm more worried about what happens in less trivial examples. [Let's face it, who wants to compute the sum of the numbers from 1 to N?]

Inspired by Don's blog post, and coincidentally working on a program where profiling points to one particular, short function as responsible for 60% of the work, I thought this would be a good time to look into core and reveal the deep secrets of my code. This is the function:

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mkAnn :: ByteString -> Annotation mkAnn = pick . B.words where pick (_db:up:rest) = pick' up $ getGo rest pick' up' (go:_:ev:_) = Ann (B.copy up') (read $ B.unpack go) (read $ B.unpack ev) getGo = dropWhile (not . B.isPrefixOf (pack "GO:"))

read $ B.unpack go Looks suspicious. You're unpacking to lists. ByteString performance rule 1: don't unpack to lists. -- Don