Re: [Scheme-reports] Are generated toplevel definitions secret?

[Jim Rees <jimreesma@x>]

On Wed, Apr 27, 2011 at 5:49 PM, John Cowan <cowan@x> wrote:

Andy Wingo scripsit:

> This question is about identifiers that are not present in the macro
> input, and which are free relative to the definition of the macro
> (not a pattern variable, not a lexical variable, not a module-level
> variable).

Ah, thanks.  Yes, letting such names leak would suck.

From an R6RS-ish (syntax-case library) point of view,  such an "introduced" identifier would be have a "mark" on it after returning from the expander.   It would not, therefore, be bound-identifier=? to a similar-named identifier already defined in your top-level without the same mark.   The only thing that could even refer to this "marked" definition would be other code generated by *same* macro call.

Of course, the effect you fear *can* be implemented on purpose from the macro with the use of datum->syntax.   And sometimes, you might even want this (think R6RS-style define-record-type with implicit constructor, predicate, accessor names).

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