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  1. (define (task lst)
  2.   (define (check lst prev?)
  3.     (if (null? lst)
  4.         #f
  5.         (let ((curr? (list? (car lst))))
  6.           (or (and prev? curr?)
  7.               (check (cdr lst) curr?)))))
  8.   (check lst #f))
  9.  
  10. (define (test lst)
  11.   (display lst)
  12.   (display " => ")
  13.   (display (task lst))
  14.   (newline))
  15.  
  16. (for-each
  17.  test
  18.  '(()
  19.    (1)
  20.    (1 2)
  21.    ((1) 2)
  22.    (1 (2))
  23.    ((1) (2))
  24.    (1 (2) 3)
  25.    ((1) 2 (3))
  26.    (1 (2) (3))
  27.    ((1) (2) 3)))
Success #stdin #stdout 0.01s 8672KB
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() => #f
(1) => #f
(1 2) => #f
((1) 2) => #f
(1 (2)) => #f
((1) (2)) => #t
(1 (2) 3) => #f
((1) 2 (3)) => #f
(1 (2) (3)) => #t
((1) (2) 3) => #t
https://ideone.com/4dmmMp
language:
Scheme (guile 2.2.4)
created:
7 years ago
visibility:
public

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