[Haskell-cafe] performance question

[Nicolas Bock]

Hi list,

I wrote a script that reads matrix elements from standard input, parses the
input using a regular expression, and then bins the matrix elements by
magnitude. I wrote the same script in python (just to be sure :) ) and find
that the python version vastly outperforms the Haskell script.

To be concrete:

$ time ./createMatrixDump.py -N 128 | ./printMatrixDecay
real    0m2.655s
user    0m2.677s
sys     0m0.095s

$ time ./createMatrixDump.py -N 128 | ./printMatrixDecay.py -
real    0m0.445s
user    0m0.615s
sys     0m0.032s

The Haskell script was compiled with "ghc --make printMatrixDecay.hs".

Could you have a look at the script and give me some pointers as to where I
could improve it, both in terms of performance and also generally, as I am
very new to Haskell.

Thanks already,

nick
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