[Haskell-cafe] I would like a clarification about Enumerators and Iteratees, please :)

Alfredo Di Napoli alfredo.dinapoli at gmail.com
Tue Oct 16 14:46:00 CEST 2012

Hi guys,

I've started playing with Iteratee and Enumerators: very cool and addictive

I have wrote this simple code:


In a nutshell, it gives back the number of occurences for a single char in
case the argument passed from the command line is a single char,
or the number of lines of the entire file.

I've tried it first on a small file (~100MB) and then on a huge one (~3GB).
As far as I understood Iteratee IO should be a smart way to do IO,
avoiding to keep the entire file in memory; what I observe in the second
case, instead, is a sort of memory leak. The memory grows and grows
until the entire machine hangs.

If I split the huge file in "small" chunks, memory comsumption is still
high but the computation terminates and is fast.

So my two questions:

a) What am I missing? Should be memory used be constant? And how can I
achieve this purpose?
b) I'm using the package enumerator because as far as I can see is the most
used. How does it compares with "iteratee"? Which of the two are more

Bye and thanks,
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