Urs Liska <[email protected]> writes:
> Hi all,
>
> I am working on a Scheme function and would like to check if I have found the
> best solution for a specific subpart. Somehow it looks more complicated than
> necessary.
>
> The function needs to test if each element of a given list is a (sub)list
> with exactly two elements. So
>
> '((1 2)(3 4))
>
> would return #t while
>
> '((5 6)(7 8 9))
>
> would return #f.
>
> My solution is
>
> \version "2.19.6"
>
> validate =
>
> #(define-scheme-function (parser location lst) (list?)
>
> (if (memv #f (map (lambda sig
Why (lambda sig ... rather than (lambda (sig) ... here and consequently
(car sig) instead of sig below?
> (and (list? (car sig))
>
> (= 2 (length (car sig))))) lst))
>
> (display "invalid")
>
> (display "valid"))
>
> (newline))
(if (every (lambda (sig) (eqv 2 (length+ sig))) lst)
(display "valid")
(display "invalid"))
--
David Kastrup
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