[Top][All Lists]

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

[Gcl-devel] Re: subtypep

From: Camm Maguire
Subject: [Gcl-devel] Re: subtypep
Date: 08 Mar 2006 15:58:20 -0500
User-agent: Gnus/5.09 (Gnus v5.9.0) Emacs/21.2


Robert Boyer <address@hidden> writes:

> Fixed? Hmmmm?
> Consider these predicates:
>   (defun foo (x) nil)
>   (defun bar (x) t)
> (subtypep '(satisfies foo) '(satisfies bar)) was NIL, T and is now NIL, NIL.
> That is a better answer and an acceptable answer.  Good.  But T, T would be
> even better, even best!
> (subtypep '(satisfies bar) '(satisfies foo)) was NIL, T and that was a better
> answer than the current NIL, NIL, which is ok but merely because it is an
> always acceptable, mealy-mouthed cop-out: "I dunno!"
> Note: I am not asking for any further work here, just thinking out loud.
> Maybe in some future life we'll open up SATISFIES predicates.  Probably a
> giant swamp.

I think swamp is accurate.  I was quite proud that we could determine
that satisfies was some unknown blob and still infer the subtypep
relationship where possible, e.g. `(and cons (satisfies foo)) 'list,
until I see that cmucl and clisp do the same.  As they do on your
examples above.  Maybe we have merely caught up.  Sigh.

Take care,

> Bob

Camm Maguire                                            address@hidden
"The earth is but one country, and mankind its citizens."  --  Baha'u'llah

reply via email to

[Prev in Thread] Current Thread [Next in Thread]