Hi all,
I'm stuck on a macro issue with the top-level and was wondering if
anyone had any thoughts.
Certain macros (I'm thinking of parts of Typed Racket) manage
communication between different parts of a program (different macros or
different instantiations of the same macro) by storing a syntax-time
table that maps, say, identifiers that should be defined in one place
and referenced in another.
The trouble is that this approach doesn't work so well at the top-level
because of the issues described in Reference ยง1.2.3.9. Namely because at
the top-level if one invocation of a macro expands to:
(my-macro) =>
(begin
(define-values (generated-id) something-to-use-later)
... other stuff ...)
and then another invocation expands to:
(my-macro) =>
(begin
(generated-id)
... other stuff ...)
you get an unbound identifier error because `generated-id` is only bound
within the first `begin` block.
Is there any way I can get around this issue? I thought maybe syntax
lifting would help out, but I need to use a particular generated
identifier and not a fresh one obtained from lifting. That and TR
catches all lifts at the top-level anyway (and sticks them in a `begin`)
so I don't think it'll help.
I also noticed that you can get around the 1.2.3.9 limitation using
`eval` if you have a non-gensymed identifier, but it doesn't appear to
help with a gensymed one.
Cheers,
Asumu
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