Hi John,
thank you for your reply ! :)
...no, not a homework...
I want to teach myself some racket and hope 'to get it' finally...
Since I am no native speaker I have the deficulty to search for
things, which names I dont know...
One example of my code is:
(define (trim-list lst)
(if (empty? lst)
lst
(cons (string-trim (car lst)) (trim-list (cdr lst)))))
(define (walk-sublists lst)
(if (empty? lst)
lst
(cons (trim-list (car lst)) (walk-sublists (cdr lst)))))
I want to avoid to call trim-list, if 'car lst' returns an empty list.
Instead 'car lst' sghould return the next non-empty list...
I will take a look in the reference manual for 'filter' and 'compose'.
Cheers
Meino
'John Clements' via Racket Users <racket-users@googlegroups.com> [16-11-16
18:26]:
>
> > On Nov 15, 2016, at 19:52, meino.cra...@gmx.de wrote:
> >
> > Hi,
> >
> > I have a list of sublists. Some of the sublists are empty.
> > The list should be processed recursevly and the resulting
> > list should no longer contain empty sublists.
>
> Is this homework?
>
> if so: can you show your test cases?
>
> if not: (filter (compose not null?) l).
>
>
> John Clements
>
> >
> > The code I have so far looks like:
> >
> > (define (step-through-list lst)
> > (if (empty? lst)
> > lst
> > (cons (process-sublist (car lst)) (step-through-list (cdr lst)))
> >
> > ....but "car" would feed empty sublists to process-sublist as any other
> > sublist. How can I "silently" skip empty sublists and even get out of
> > the recursion without harm (if the last sublist is empty) without
> > switching to iteration?
> > Is there something like "car-not-empty" ? ;)
> > Or do I oversee the obvious here...? ;)))
> >
> > Thank you vary much for any help in advance!
> > Cheers
> > Meino
> >
> >
> > --
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