On Tue, 3 May 2011, Arthur A. Gleckler wrote:

>>
>> Because expressions should be invariant under alpha renaming.  In other
>> words,
>> the expression
>>
>
> But wouldn't it also be reasonable to say that COND establishes a local
> scope in which ELSE is bound?  The alpha-renaming argument wouldn't work
> then.

That brings us into the territory of unhygienic macros.  One problem with
unhygienic macros is that they don't compose well.  See this thread
http://lists.racket-lang.org/users/archive/2009-January/029784.html
for examples of the kind of problems one might run into.