Re: Issue: LET-TOP-LEVEL (version 1)

[Pavel.pa@Xerox.COM]

First, I would claim that this is a ``clarification'' as opposed to an
``addition''.  I see no language in CLtL to support the belief that DEFUN can
only be used in certain scopes.  This reminds me of the debate over whether or
not the compiler is required to be reentrant; of course it is, for the same
reason that MAP is, for example: it's just another function with a particular
contract.

In any case, I don't oppose the proposal because I think it's important for
implementors to support this style.  I have some other comments, though.

Why does the proposal not cover all of the defining forms?  In particular, why
not DEFMACRO?  It makes just as much sense for the expansion function to be a
closure.  Of course, the compiler will not be able to expand uses of that macro
later in the same file, since it can't provide the proper lexical environment to
the expansion function, but that just means that this style would have to be
used in a separate file that is loaded before compilation of uses of the macro.
The same goes for the defining forms DEFSTRUCT, DEFTYPE, etc.

I not particularly happy with the explicit use of the term ``top-level'', but
until Rob's compiler proposal gets a fair hearing, I don't see any way around
it.

For the current practice section, Xerox Lisp also implements the proposed
behavior.