[r6rs-discuss] [Formal] Add symbol=? and boolean=?

From: John Cowan <cowan>
Date: Sat Feb 10 13:30:37 2007

Per Bothner scripsit:

> [I]t seems that if you were to design a language from scratch you
> probably make a clearer distinction between values and objects.

Actually the distinction is quite clear: something is a value
if it's immutable, and not a value if it is mutable. Henry Baker
nailed this with his EGAL predicate, which is value equality
on immutable things and object identity on mutable things: see
http://home.pipeline.com/~hbaker1/ObjectIdentity.html .
(This is a very interesting paper, and I recommend that anyone
interested in the semantics of equality predicates read it.)

-- 
Yes, chili in the eye is bad, but so is your    John Cowan
ear.  However, I would suggest you wash your    cowan_at_ccil.org
hands thoroughly before going to the toilet.    http://www.ccil.org/~cowan
        --gadicath
Received on Sat Feb 10 2007 - 13:30:25 UTC

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