Questions, comments and clarifications on clarifications

[edsel!eb@su-navajo.arpa (Eric Benson)]

82.  Is it gratuitous pseudo-generality to allow an arbitrary number of
arguments to XOR, instead of requiring exactly two?  Give an example.

107.  GET-SETF-METHOD should definitely take an optional environment
argument.  Calling MACROEXPAND is seldom a good thing to do in a
program, even a compiler, since there may be intermediate macros which
require special handling.  In this case an intermediate macro may have a
setf method.  Even though a user program is probably incorrect if it
does not supply the environment argument to GET-SETF-METHOD, we should
make it optional for maximum compatibility with the existing standard.

Along with allowing an optional environment argument to GET-SETF-METHOD,
it is important to allow DEFINE-SETF-METHOD to take an &ENVIRONMENT
argument.  It is also important that macros defined with
DEFINE-MODIFY-MACRO correctly pass the environment to GET-SETF-METHOD;
this belongs in an implementation note.

A hard question: Does MACROLET shadow a setf method or not?

(DEFUN LOSER (X)
  (CAR X)

(DEFUN SET-LOSER (X Y)
  (SETF (CAR X) Y))

(DEFSETF LOSER SET-LOSER)

(DEFUN LOSSAGE (X Y)
  (MACROLET ((LOSER (X)
	       `(SYMBOL-VALUE ,X)))
    (SETF (LOSER X) Y)))

Does LOSSAGE call SET-LOSER or SET?

130.  I think it is better to say that anything other than a symbol or
an integer at the top level in a TAGBODY is evaluated normally, rather
than having special rules.  This is not a major point, however.

144. Can an FLET shadow a DEFMACRO?

(DEFMACRO FOO ()
  )

(DEFUN BAR ()
  (FLET ((FOO () ...))
    (MACROLET ((BAZ (&ENVIRONMENT ENV)
		 (IF (MACRO-FUNCTION 'FOO ENV)
		     "Lose"
		     "Win")))
      (BAZ))))

Does (BAR) return "Win" or "Lose"?  (See if you can guess what I think
it should do.)

268.  There's no need to mention that COPY uses the user-specified copy
function for structures, since the user only specifies a @i(name) for the
function; the system supplies the definition.

Along the same lines, there really should be a true structural equality
comparison function, i.e. a case-sensitive EQUALP, or EQUAL which
descends into arrays and structures.  It would also be nice to have a
graph isomorphism comparison function, but perhaps this is beyond the
scope of Common Lisp.  I only brought it up because it cannot be written
portably so that it descends into all structures.  How about graph
isomorphism modulo gensyms?

293.  ROW-MAJOR-AREF should be SETFable.

295.  Also include SETF of AREF, ROW-MAJOR-AREF, and SETF of
ROW-MAJOR-AREF among the functions which can access beyond the fill
pointer of an array.