I have some experience writing small tools in Haskell and I find it very intuitive to use, especially for writing filters (using
interact) that process their standard input and pipe it to standard output.
Recently I tried to use one such filter on a file that was about 10 times larger than usual and I got a
Stack space overflow error.
- Avoid recursive function calls that are not tail-recursive (this is valid for all functional languages that support tail-call optimization).
seqto force early evaluation of sub-expressions so that expressions do not grow too large before they are reduced (this is specific to Haskell, or at least to languages using lazy evaluation).
After introducing five or six
seq calls in my code my tool runs smoothly again (also on the larger data). However, I find the original code was a bit more readable.
Since I am not an experienced Haskell programmer I wanted to ask if introducing
seq in this way is a common practice, and how often one will normally see
seq in Haskell production code. Or are there any techniques that allow to avoid using
seq too often and still use little stack space?