🚀 go-pugleaf

In article <10367.9208251621@subnode.aiai.ed.ac.uk> jeff@aiai.edinburgh.ac.uk (Jeff Dalton) writes:
>> Since the above program isn't conforming, anything is legal. 
>
>If this is what the dpANS says, I think it should change.  

Actually, I think I was overstating it.  Perhaps I should have said, "since
it isn't conforming, the standard doesn't specify which one it returns."

>							    Does anyone
>seriously think that the behavior of the following program is or
>should be completely undefined, ie that it might be anything at all?
>
>(defun g ()
>  (flet ((f (x) x))
>    (typep #'f 'compiled-function)))

Lisp's introspective facilities make it difficult to use general rules
about interpreter/compiler equivalence (we considered getting rid of the
COMPILED-FUNCTION type, though).  I agree that it's not totally undefined,
but it isn't well-defined whether it returns T or NIL.  Once it's been
compiled it's guaranteed to return T, but before then it could return
either.  On some systems it will return T all the time, even though these
systems use a traditional interpreter; to simplify FUNCALL and APPLY, they
implement interpreted functions as a closure of a compiled interpreter
function over the lambda expression.

-- 
Barry Margolin
System Manager, Thinking Machines Corp.

barmar@think.com          {uunet,harvard}!think!barmar