[Haskell-beginners] Brainfuck interpreter stack overflow

[Daniel Fischer]

Am Mittwoch 20 Januar 2010 16:45:41 schrieb Edgar Klerks:
> Hello,
>
> I just started using haskell and found it many uses for it (mainly for
> scripting purposes at the moment). Now, I have written a brainfuck
> parser and interpreter in haskell, but it produces a stack overflow if
> the program runs too long and I don't understand why. I thought I made
> the interpreter loop tail recursive, which I understood is the most
> common cause of a stack overflow. Can someone help my find my fault? I
> somehow miss something. I added the program as attachment.
>
> Thanks for your help.
>
> With kind regards,
>
> Edgar Klerks

A quick look revealed that you use Control.Monad.State, which defaults to 
Control.Monad.State.Lazy. That is very often too lazy for longer 
calculations and produces a stack overflow.
Maybe changing the import to Control.Monad.State.Strict helps (that isn't 
entirely strict either, but often reduces the opportunities for building 
large thunks sufficiently).