Defun inside Let

[David C. Plummer <DCP@SCRC-QUABBIN.ARPA>]

    Date: Thu, 30 Jan 1986  20:13 EST
    From: Rob MacLachlan <RAM@C.CS.CMU.EDU>

	I don't have answers for any of those.  My personal feeling is
	that DEFUN that requires a non-null lexical environment, such as
	created by LET, is a timebomb ticking quickly.

    I think many of the cited problems are contingent in the assumption
    that COMPILE lets you do everything you want to do.  You are bothered
    mostly by programming environment issues which Common Lisp mostly
    doesn't address.

That's right, I am bothered by programming environment.  That isn't
necessarily an issue to the people who use the code, but it sure is an
issue to those that write it and have to debug it.  [Actually, the users
never come into it; for all they know the program they are running is
written in Ada.  This is only an issue for developers.]  I agree it is
probably not in CL's domain to address these issues, but it shouldn't
prohibit it.  Maybe another example?

(let ((counter 0))
  (defun hairy-function-counter ()
    counter)
  (defun hairy-function (arg1 ...)
    (incf counter)
    ...big-and-hairy-compuation-bound-to-get-
    called-a-lot-and-have-bugs-that-need-fixing...))

Why, during my debugging cycle, should I be forced to have the counter
reset to 0 each time I need to change hairy-function?

    Date: Thu, 30 Jan 86 13:37:13 pst
    From: mips!escargot.earl@glacier (Earl Killian)

    No one has suggested that making DEFUN inside of LET not work is the
    right thing (people have suggested that it may not be required by the
    current wording of the Common Lisp manual).  If someone feels that
    DEFUN inside of LET shouldn't work, they ought to speak up!

I have reservations.