Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!uunet!zephyr.ens.tek.com!tekcrl!tekchips!kend
From: kend@tekchips.LABS.TEK.COM (Ken Dickey)
Newsgroups: comp.lang.scheme
Subject: Re: Bogus bug in MIT-Scheme
Message-ID: <5835@tekcrl.LABS.TEK.COM>
Date: 23 Mar 90 22:55:51 GMT
References: <9003221201.AA11816@zurich.ai.mit.edu> <9003231556.aa09018@mintaka.lcs.mit.edu>
Sender: news@tekcrl.LABS.TEK.COM
Reply-To: kend@mrloog.WR.TEK.COM (Ken Dickey)
Organization: Tektronix, Inc., Beaventon,  OR.
Lines: 51


Here are a couple of somewhat more efficient versions of a portable
string->cannonical-symbol.  The only difference is the use of DO vs
named LET {some people particularly dislike one or the other}.

[Just for fun... or should we discuss style and esthetics for a few
weeks? 8^]

-Ken Dickey

;;==================

(define STRING->CANNONICAL-SYMBOL
  (let ( (case-squasher (if (eq? 'a (string->symbol "A"))
                            char-upcase
			    char-downcase))
       )
   (lambda ( <string> )
      (let* ( (str-len (string-length <string>))
	      (decaseified-string (make-string str-len))
            )
        (let loop ( (index (- str-len 1) ) )
	     (string-set! decaseified-string
		  	  index
			  (case-squasher (string-ref <string> index)))
             (if (> index 0)
		 (loop (- index 1))
		 (string->symbol decaseified-string))
   ) )  )
) )

;;==================

(define STRING->CANNONICAL-SYMBOL
  (let ( (case-squasher (if (eq? 'a (string->symbol "A"))
                            char-upcase
                            char-downcase))
       )

    (lambda ( <string> )
      (let* ( (str-len (string-length <string>))
	      (decaseified-string (make-string str-len))
      	    )

	(do ( (index (- str-len 1) (- index 1)) )
	    ( (< index 0) (string->symbol decaseified-string) )
            (string-set! decaseified-string
                         index
                         (case-squasher (string-ref <string> index)))
    ) ) )
) )