[Haskell-cafe] Function composition confusion
lemming at henning-thielemann.de
Wed Apr 27 09:37:19 EDT 2005
On Wed, 27 Apr 2005, Anuj Seth wrote:
> Excuse the newbie'ness of my question.
> Saw an example in Two Dozen Questions by Rexx Page.
> blocks blockSize =
> takeWhile ( not . null ) . map fst .
> iterate (splitAt blockSize . snd) . splitAt blockSize
> What is the meaning of the . operators outside the parentheses ?
The same as inside. :-)
(splitAt blockSize) transforms a list to a pair of lists. So imagine a
list input at the right of (splitAt blockSize) and a pair output at the
left. This pair is piped into the 'iterate' part which transforms a list
of pairs into a list of pairs of lists. This in turn is piped to (map fst)
and so on.
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