Formal comment #5 (defect)

Implementing Common Lisp's defmacro is not straightforward
Reported by:	Pascal Costanza

Component:	macros
Version:	5.91

Section 17.6, page 113, last paragraph, states that "Using lisp-
transformer, defining a basic version of Common Lisp's defmacro is a
straightforward exercise."

This is misleading. It is true that Common Lisp's destructuring
facilities in its macro lambda lists, as well as the inclusion of
optional and keyword arguments, are merely syntactic sugar. However,
Common Lisp macros also provide access to the lexical environment of a
macro invocation via environment objects. See Sections 3.4.4 and
3.1.1.4 in the ANSI Common Lisp specification [1]. I doubt that it's
straightforward to reimplement environment objects using syntax-case.

I suggest to drop this sentence completely. The preceding paragraph
already mentions that lisp-transformer can be used to "write macros in
the style of old Lisp macros", and that seems to be a sufficient
motivation for this example.

[1] http://www.lispworks.com/documentation/HyperSpec/Front/index.htm

RESPONSE:

Agreed.  The sentence will be removed.