/usr/lib/sublist.scm is in scheme9 2013.11.26-1.
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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 | ; Scheme 9 from Empty Space, Function Library
; By Nils M Holm, 2010
; Placed in the Public Domain
;
; (sublist list integer1 integer2) ==> list
;
; Return a fresh list formed from the members of LIST beginning with
; index INTEGER1 (inclusive) and ending with index INTEGER2 (exclusive).
;
; Example: (sublist '(a b c d e) 2 4) ==> (c d)
; (sublist '(a b c d e) 2 2) ==> ()
(define (sublist x p0 pn)
(let ((k (length x)))
(cond ((<= 0 p0 pn k)
(do ((i p0 (+ 1 i))
(in (list-tail x p0) (cdr in))
(out '() (cons (car in) out)))
((= i pn)
(reverse! out))))
(else
(error "sublist: bad range" (list p0 pn))))))
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