;"sc4opt.scm" Implementation of optional Scheme^4 functions for IEEE Scheme ;Copyright (C) 1991, 1993 Aubrey Jaffer ; ;Permission to copy this software, to modify it, to redistribute it, ;to distribute modified versions, 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 warranty 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-copy string-append) ;@ (define (string-fill! s obj) (do ((i (- (string-length s) 1) (- i 1))) ((< i 0)) (string-set! s i obj))) ;@ (define (vector-fill! s obj) (do ((i (- (vector-length s) 1) (- i 1))) ((< i 0)) (vector-set! s i obj)))