Ramana,
On Sun, 21 Jun 2009 03:03:42 -0400, Ramana Kumar <[email protected]>
wrote:
> Aaron you have a good idea, but the choice for #'a is much more
> important than it seems. For example, if you define your
> bound-identifier? macro at the top level of some library or script
> that imports (rnrs), then it will incorrectly say "define" (and other
> (rnrs) imports) is unbound. You are inadvertently picking up the wrap
> of the identifier #'a.
This is neither unintentional nor unexpected. As I mentioned, the whole
reason this works is because I am grabbing the top-level wrapping on a
syntax and using that to introduce a binding of the same form as the
first. The code I gave only works for lexically scoped values, and not for
imported or top-level definitions. As you know, the reason that this works
is because I am created a top-level syntax that has the same reference as
the given identifier would *if* the identifier is not scoped at some later
point, such as inside of a LET or the like. The definition of
'free-identifier=?' states that all identifiers are presumed to be
explicitly bound at the top-level. This makes it impossible to distinguish
whether an identifier is bound at the top level or not using
'free-identifier=?'. Thus, I can see no way of identifying what is bound
and what is not at the root level of a library form or at the top-level
using such a simple technique.
Sincerely,
Aaron W. Hsu
--
Of all tyrannies, a tyranny sincerely exercised for the good of its
victims may be the most oppressive. -- C. S. Lewis
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