-----Ursprüngliche Nachricht----- Von: Bruno Schneider Gesendet: 24.03.2010 13:56:32 An: hugs-users@haskell.org Betreff: Re: [Hugs-users] stack overflow in tail recursive function
>On Wed, Mar 24, 2010 at 7:27 AM, Daniel Fischer wrote: >[...] >> >> and this expression is only evaluated if necessary. factorial 20000 builds a >> thunk of 20000 nested multiplications, this is tried to evaluate when the >> value is demanded for printing, but the expression is too deeply nested to >> fit on the stack. >> > >So it goes to the stack, hum? It thought it would be just a pointer to >some computation type on the heap. Well, the thunk is built on the heap, that's correct, but when it's evaluated, things go on the stack. > >Anyway, thanks for the detailed answer. I asked here because I didn't >test that code on any other compiler/interpreter, so it could be >something related to hugs implementation. > That's okay, but as a rule of thumb, if you don't know that it's implementation-specific, haskell-cafe or beginners (depending on what sort of answer you want) is the better choice; hugs-users or glasgow-haskell-users are less frequented. In this case, the behaviour is a little implementation-dependent, if you use GHC and compile with optimisations, the strictness-analyser should see that the result of the multiplication is needed and the compiler should make it strict by itself. (I currently have no access to a computer with GHC installed, so I can't check that it does indeed.) > >-- >Bruno Schneider >http://www.dcc.ufla.br/~bruno/ Cheers, Daniel _______________________________________________ Hugs-Users mailing list Hugs-Users@haskell.org http://www.haskell.org/mailman/listinfo/hugs-users
