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;"sc4opt.scm" Implementation of optional Scheme^4 functions for IEEE Scheme
;Copyright (C) 1991, 1993 Aubrey Jaffer.
;
;Permission to copy this software, to redistribute it, and to use it
;for any purpose is granted, subject to the following restrictions and
;understandings.
;
;1. Any copy made of this software must include this copyright notice
;in full.
;
;2. I have made no warrantee or representation that the operation of
;this software will be error-free, and I am under no obligation to
;provide any services, by way of maintenance, update, or otherwise.
;
;3. In conjunction with products arising from the use of this
;material, there shall be no use of my name in any advertising,
;promotional, or sales literature without prior written consent in
;each case.
;;; Some of these functions may be already defined in your Scheme.
;;; Comment out those definitions for functions which are already defined.
;;; This code conforms to: William Clinger and Jonathan Rees, editors.
;;; Revised^4 Report on the Algorithmic Language Scheme.
(define (list-tail l p)
(if (< p 1) l (list-tail (cdr l) (- p 1))))
(define (string->list s)
(do ((i (- (string-length s) 1) (- i 1))
(l '() (cons (string-ref s i) l)))
((< i 0) l)))
(define (list->string l) (apply string l))
(define string-copy string-append)
(define (string-fill! s obj)
(do ((i (- (string-length s) 1) (- i 1)))
((< i 0))
(string-set! s i obj)))
(define (list->vector l) (apply vector l))
(define (vector->list s)
(do ((i (- (vector-length s) 1) (- i 1))
(l '() (cons (vector-ref s i) l)))
((< i 0) l)))
(define (vector-fill! s obj)
(do ((i (- (vector-length s) 1) (- i 1)))
((< i 0))
(vector-set! s i obj)))
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