Re: Mutable objects as mapping keys
Stephen J Bevan (bevan@computer-science.manchester.ac.uk)
Fri, 2 Apr 1993 15:19:53 +0200
>>>>> On Tue, 30 Mar 93 00:00:10 EST, Tim Peters <tim@ksr.com> wrote:
Tim> I do note that various LISPs implement dictionaries as "association
Tim> lists", and that the usual access function "assoc" uses the "equal"
Tim> predicate to see whether a key is present; and "equal" does usually
Tim> compare deep structure (with undefined behavior in the presence of
Tim> loops).
Scheme currently has "member" which does the above and "memq" which
uses pointer equality.
Tim> Any LISP'ers out there who think that's important to do?
This lisper prefers to let the user decide allow a user defined
comparision function to be used.
bevan