Re: [Haskell-cafe] Slow IO

Daniel Fischer writes:

Yes, I did it wrong, but I didn't keep anything (but the first and last Char of each line) in memory on purpose. I hoped for the lines to be read one after the other, head and last extracted [...] Profiling (hy,hc) shows that the IO part of the programme holds on to tons of lists - that couldn't be anything but parts of the file-contents, I believe.

Chances are that you don't evaluate these characters right away, so what you are retaining is just unevaluated thunks that refer to the lines themselves. So the fix is to make the extraction of the characters stricter. -k -- If I haven't seen further, it is by standing in the footprints of giants