[Haskell-cafe] Re: Write Haskell as fast as C.
westondan at imageworks.com
Fri May 16 18:10:09 EDT 2008
Dan Weston wrote:
> Ketil Malde wrote:
>>> 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:"))
> It seems at first face miraculously coincidental that the dropWhile in
> the getGo definition knows to stop dropping when there are exactly 4
> elements, in order to match the pattern in the second parameter of the
> pick' definition, whose argument is provided by (getGo Rest).
> What magic makes this true? Just curious...
I didn't mean "exactly 4", but "at least 3". Otherwise, I'm still
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