Re: default stack size

[Lynn Winebarger]

Viktor Pavlenko wrote:
> > > > > > "bt" == barney toma <address@hidden> writes:
>
>     bt> I receive a stack overflow error when creating a list of 500
>     bt> entries.
>
>     bt> (define (rep n)          ;(rep n) ==> (n n-1 n-2  ... 1)
>     bt>     (cond ((= n 0) '())
>     bt>        (t (cons n (rep (- n 1) )))))
>     bt> (rep 500)
>
>     bt> I believe the default stacksize is larger than this.  So I'm
>     bt> wondering if this indicates some abnormal condition such as a
>     bt> possible hardware problem.
>
> I don't think so, unless I have a hardware problem too. A tail-
> recursive procedure will give you a list as long as you wish (but in
> ascending order):
>
> (define (rep n ls)
>   (cond ((= n 0) ls)
>         (else (rep (- n 1) (cons n ls)))))
>
> (rep 10000 '())
>
> I think by setting the stack limit so low (389) they encourage you to
> write tail recursive procedures (correct me if I'm wrong).

   Yeah, but why not get it in the right order:

(define (rep n)
  (let loop ((n n)
             (k (lambda (v) v)))
    (if (= n 0)
        (k '())
        (loop (- n 1)
          (lambda (v)
            (k (cons n v))))))

   Though reliance on the stack may be/is probably more efficient.  All this
version does is allocate the stack in the heap, one disconnected frame at a 
time.

Lynn