Re: [Haskell-cafe] Patterns for processing large but finite streams

Eugene Kirpichov writes:

2011/7/1 Heinrich Apfelmus :

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Eugene Kirpichov wrote:

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I'm rewriting timeplot to avoid holding the whole input in memory, and naturally a problem arises:

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Plain old lazy lists?

Heretic! :-) I generally have written a bunch of programs that do things that way, and I think it works pretty well with a couple of caveats: 1. Make sure you collect data into strict data structures. Dangerous operations are addition and anything involving Data.Map. And use foldl'. 2. If you plan on working on multiple files, extra care might be needed to close them, or you'll run out of file descriptors. As long as you avoid these pitfalls, the advantage is very clean and simple code.

Plain old lazy lists do not allow me to combine multiple concurrent computations, e.g. I cannot define average from sum and length.

Yes, this is clunky. I'm not aware of any good solution. -k -- If I haven't seen further, it is by standing in the footprints of giants