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