diff1p? -------- A simple lisp problem

On 6/15/2024 1:08 PM, HenHanna wrote:

On 6/14/2024 8:45 PM, B. Pym wrote:

Frank Schwieterman wrote:
>

I am Lisp beginner and I am doing a simple execise on lisp. I was asked
to write a lisp program , by using either recursion or do, to return
true if the difference between each successive pair of the them is 1. (or LESS)
>
ie:
>

(difference '(2 1))

T

(difference'(3 4 5 6 5 4))

T

(differnce '(3 4 5 3))

NIL

  ....

>
(defun difference (param)
      (if (> (length param) 1)
         (if (<= (abs (- (first param) (first (rest param)))) 1 )
            (difference (rest param))
            nil
            )
         T
         )
      )

looks good.   except for   CADR (second)   and   )  )  )

  (define (diff1p?  x)
   (or (null? x)
       (null? (cdr x))
       (and (= 1 (abs (- (car x) (cadr x)) ))
            (diff1p? (cdr x)) )))
 

>
Gauche Scheme
>
(define (diff1? xs)
   (every
     (lambda (a b) (= 1 (abs (- a b))))
     xs
     (cdr xs)))
>
(diff1? '(2 3 4 3 4 5 6 7 8 9 8))     ===>  #t

 

(diff1? '(2 3 4 3 4 5 6 7 8 9 8 0))   ===>  #f

in Scheme (Gauche),  is there a way to write it  more like this ?
def diff1(x):
     return all( abs(x[i] - x[i+1]) == 1    for i in range(len(x)-1)  )