On Sun, Apr 19, 2009 at 9:48 AM, Manlio Perillo <manlio_peri...@libero.it>wrote:
> Henning Thielemann ha scritto: > > > > On Tue, 14 Apr 2009, rodrigo.bonifacio wrote: > > > >> I guess this is a very simple question. How can I convert IO [XmlTree] > >> to just a list of > >> XmlTree? > > > > The old Wiki had: > > http://www.haskell.org/wikisnapshot/ThatAnnoyingIoType.html > > > > Should be ported to the new Wiki since it is a FAQ ... > > Note that it is not always possible to separate IO from pure code. > As an example, consider an HTTP 1.1 server that read a request body > containing a number for each line, and return a response body containing > the sum of the numbers. What? sumRequest :: String -> String -- strips header, sums numbers, returns response sumServer :: IO () -- reads from socket, writes sumRequest to socket And many other permutations, with differing degrees of laziness and parametericity. Luke
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