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Add list-head, list-tail.

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* module/mes/scm (list-head, list-tail): New function.
This commit is contained in:
Jan Nieuwenhuizen 2016-12-17 14:44:34 +01:00
parent 738eabbe0e
commit dab37a844b
1 changed files with 8 additions and 0 deletions
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8
module/mes/scm.mes
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@ -32,6 +32,14 @@
(define (list . rest) rest) (define (list . rest) rest)
(define (list-head x n)
(if (= 0 n) '()
(cons (car x) (list-head (cdr x) (- n 1)))))
(define (list-tail x n)
(if (= 0 n) x
(list-tail (cdr x) (- n 1))))
(define-macro (case val . args) (define-macro (case val . args)
(if (null? args) #f (if (null? args) #f
(let ((clause (car args))) (let ((clause (car args)))