[Haskell-cafe] An example of enumerator processing some data between input and output

[Paul Sujkov]

Actually, I may be quite wrong with the task. While duplexing the input is
an interesting thing to do, actually I need to pipeline output of one
consumer to another (outputting text after making some internal
representation - with Show instance - with the parseData). The answer to
this one should be easy, but I still do not see it.

On 19 April 2011 20:10, Paul Sujkov <psujkov at gmail.com> wrote:

> Hi haskellers,
>
> I played a bit with the enumerator package, and I'm quite stuck with the
> question how to duplex data to two (or more) consumers using combinators
> from xml-enumerator (for example) package. What I mean is:
>
> main = withFile "out.xml" WriteMode $ \h ->
>        parseFile "in.xml" decodeEntities $
>        (joinI $ renderText $$ iterHandle h) >> (force "data required"
> parseData)
>
> where parseData is a simple xml-enumerator parser. Combining consumers in
> such a way I can get text being output to the file "out.xml" (like in the
> example given) or parsed with parseData (if I switch the order of the
> consumers), but not both. Can anybody tell me how to make a pipe (input ->
> process -> output) to have text both parsed and then put back to the file?
> While pretty straightforward with the arrow approach, it doesn't seem
> obvious to me with the iteratees :(
>
> --
> Regards, Paul Sujkov
>



-- 
Regards, Paul Sujkov
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