[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
- To: info-mcl
- Subject: Re: functionp
- From: firstname.lastname@example.org (Bill York)
- Date: 6 Nov 92 00:16:29 GMT
- In-reply-to: email@example.com's message of 5 Nov 92 16:57:36 GMT
- Newsgroups: comp.lang.lisp.mcl
- Organization: Lucid, Inc.
- References: <9211051555.AA17957@cambridge.apple.com>
- Reply-to: York@Lucid.COM
- Sender: firstname.lastname@example.org
In article <9211051555.AA17957@cambridge.apple.com> email@example.com (Bill St. Clair) writes:
>When you have a function defined, say (defun junk (x) ... ),
>and you try:
>you get NIL.
>Is this not a bug?
At the bottom of p. 102 of CLtL2, it says:
"X3J13 voted in June 1988 <90> to define
(functionp x) = (typep x 'function)
Because the vote also specified that types CONS and SYMBOL are disjoint
from type FUNCTION, this is an incompatible change; now FUNCTIONP is in
fact always false of symbols and lists."
This damned issue just won't go away! In CLTL-1 Lisps, users are
always complaining that FUNCTIONP on any symbol returns T. In
CLTL-2/ANSI Lisps people get confused the other way. In CLIM we wrote
a thing called FUNCALLABLE-P, which returned T if the thing was a
function or a symbol with a function in the function cell (I don't
think we checked for a lambda-expression, but we probably should