[Haskell-cafe] Understanding Iteratees

Arnaud Bailly arnaud.oqube at gmail.com
Wed Oct 27 03:02:36 EDT 2010


Hello,
I am trying to wrap my head around the concept of Iteratee reading the
article by John Lato in Monad Reader issue 16
(http://themonadreader.files.wordpress.com/2010/05/issue16.pdf). I
followed the "advice" on page 34:

"I have frequently heard reports from Haskellers (including highly-talented and
experienced users) that the only way they could understand enumeration-based
I/O was by re-implementing it themselves."

and so reimplemented this code in Java which is, for better and worse,
my current professional language (and there really is no point in
writing my own 50th iteratee code...).

I have a question about iteratees composition and their behaviour. I
tried to use the throbber code to display progress while writing a
file, without using enumeratees which are introduced later on in the
article, but failed. I can bind the two iteratees together, but the
writer iteratee consumes the stream of characters to write before
handing over the control to the throbber iteratee which has nothing to
count. Did I miss something ?

Thanks in advance,
Arnaud


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