I noticed that just after posting.
I changed to:
(define (length2 lst)
(define (l-iter l count)
(if (null? l) count
(l-iter (cdr l) (+ count 1))))
(l-iter lst 0))
Must get better at spotting obvious mistakes...
On 20 November 2013 11:27, Pierpaolo Bernardi <[email protected]> wrote:
> On Wed, Nov 20, 2013 at 12:09 PM, Bo Gus <[email protected]> wrote:
> > My tail recursive implementation of length is like this:
> >
> > (define (length2 l)
> > (define (l-iter l count)
> > (if (null? 1) count
> > (l-iter (cdr l) (+ count 1))))
> > (l-iter l 0))
>
> > I am fairly new to scheme. What am I doing wrong?
>
> You wrote (null? 1), which is always false. Note 1 instead of l.
>
> Cheers
>
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