The Environment

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

    Date: 2 Apr 86 12:27:00 EST
    From: "BACH::GREEK" <greek%bach.decnet@hudson.dec.com>

    Whew, I have to be careful what I imply in my messages.  I certainly
    wasn't suggesting that we define the internal format of the environment,
    only how the user sees it in terms of interface.  Mr. Plummer and I
    agree on this point.

    Still, do you think we can all agree on the interface, and thus the
    semantics?

I think we should give it a try.  I think what you will find are three
things:
 -1- Things everybody agrees on, e.g.,
	.defun variable-defined-p symbol &optional env
	returns a keyword which is the usage of the variable, one of
	NIL (unknown)
	:SPECIAL
	:LEXICAL
	:CONSTANT
	<other> (e.g., :INSTANCE)
 -2- Things not everybody agrees on
 -3- Things which are down-and-out hard, e.g.,
	"Which PROG is belongs with this GO-TAG?"

I just realized this gets more complicated because there are two classes
of programs that are using something called an 'environment' for
potentially different reasons.  One class is the interpreter, which does
know something about GO tags, but the source code of the PROG isn't
necessarily in the environment.  The other class is a code walker or
compiler, which uses a much higher degree of bookkeeping and annotation.