[plt-scheme] Switching to Scheme

From: Eli Barzilay (eli at barzilay.org)
Date: Mon Jul 3 02:34:55 EDT 2006

On Jul  3, Matt Jadud wrote:
> FWIW, I tend to use symbols and integers for keys. You can get from 
> strings to symbols with 'string->symbol', and from lists to symbols 
> with... (string->symbol (list->string <ls>)). The latter looks expensive 
> in the long run. If you're able to, just use symbols in the first place. 
>   I've often used integers for keys, but perhaps someone can tell us 
> whether this is a good idea or not for hash tables using 'eq?' as an 
> equality test.

It works for "small" integers -- until you get beyond `fixnums', on a
32-bit OS:

  > (expt 2 30)
  > (eq? 1073741824 1073741824)
  > (eq? 1073741823 1073741823)

On a 64 bit platform "small" is much bigger...  (And the 32-bit limit
is fine, since MzScheme won't work on 16-bit platforms.  ("fine" if
you stick with MzScheme.))

          ((lambda (x) (x x)) (lambda (x) (x x)))          Eli Barzilay:
                  http://www.barzilay.org/                 Maze is Life!

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