What happens if you use modify' <http://hackage.haskell.org/package/transformers-0.4.3.0/docs/Control-Monad-Trans-State-Strict.html#v:modify-39-> instead of modify? A common gotcha with Writer and State is that even the "strict versions" of these monads aren't strict in the accumulators. You have to explicitly use modify' in the case of State.
On Saturday, August 15, 2015 at 12:52:09 PM UTC+2, Alexey Raga wrote: > > Hi All, > > I have noticed that as soon as I introduce StateT into my pipeline the > memory consumption increases a lot, and it keeps increasing until the > program stops. > > Here is a simple counter example, but even this one reproduces the problem: > > counter :: Pipe a a (StateT Integer IO) () > counter = do > x <- await > S.modify(+1) > yield x > counter > > Piping a very large file (~40M rows) through a simple in/out pipeline only > consumes 3mb of memory, but once I introduce this "counter" step the memory > consumption keeps increasing up to ~700mb when the pipeline finishes. > > Am I doing it wrong? And what would be the correct way of implementing > such a "stateful" Pipe? > > Cheers, > Alexey. > -- You received this message because you are subscribed to the Google Groups "Haskell Pipes" group. To unsubscribe from this group and stop receiving emails from it, send an email to haskell-pipes+unsubscr...@googlegroups.com. To post to this group, send email to haskell-pipes@googlegroups.com.
