On Sun, Apr 19, 2009 at 9:48 AM, Manlio Perillo <manlio_perillo@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