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Date: Tue, 6 Dec 88 21:46:27 PST
From: Jon L White <firstname.lastname@example.org>
re: There seems to be nothing in CLtL that answers the question:
"is x a legal type specifier?"
At the meeting that founded the X3J13 committee (on 6-Dec-85), Guy Steele
circulated a list of "non-controversial issues" and "Clarifications"
which included the following addition [typos faithfully reproduced]:
"(*) 51 Add a newefunction TYPE-SPECIFIER-P that is true of valid type
specifiers and fals of all other Lisp objects. Note that the use of
DEFSTRUCT and DEFTYPE can change the behavior of TYPE-SPECIFIER-P over
Sad to say, this and many other "non-controversial" items included in
Guy's list of "Clarifications", has never been brought up in the X3J13
"Cleanup" subcommittee. However, Lucid's 3.0 release includes such
How do you define "valid type specifier"?
(deftype foo (x)
(typep 'yow '(foo a))
==> Error taking CAR of the symbol A.
(type-specifier-p '(foo a))
I would guess probably T, but then, how do you word the definition?
If not, how do you define it?