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From: raja@copper.ucs.indiana.edu (Raja Sooriamurthi)
Newsgroups: comp.lang.scheme
Subject: Re: Explode/Implode Query
Message-ID: <raja.672349553@copper>
Date: 22 Apr 91 19:45:53 GMT
References: <1991Apr22.180734.21661@cunixf.cc.columbia.edu>
Sender: news@bronze.ucs.indiana.edu (USENET News System)
Organization: Indiana University
Lines: 36

betsey@cunixf.cc.columbia.edu (Elizabeth Fike) writes:

>Today, in my Scheme class, the professor mentioned the functions
>explode and implode, are found in PC-Scheme, but in no
>other current versions of Scheme.  As these functions seem
>extremely useful, I am curious as to why they are not found in
>MIT Scheme version 7 (for example).  

Chez Scheme provides these functions under sicp mode (by doing
(support-sicp) )

But you can define these function yourself in any R3.99 scheme as
below:

; (explode 'apple) => (a p p l e)
; (implode '(a p p l e)) => apple
; (eq? 'apple (implode (explode 'apple))) => #t

(define explode
  (lambda (sym)
    (map string->symbol
	 (map string
	      (string->list (symbol->string sym))))))

(define implode
  (lambda (s*)
    (string->symbol
      (apply string-append
	     (map symbol->string s*)))))

-Raja


---
Raja Sooriamurthi                          |   Computer Science Department
raja@cs.indiana.edu	                   |       Indiana University