Reflecting on the lexical environment at macro expansion time

[William J. Bowman]

I'm trying to write a macro that reflects on which identifiers are in scope in
the environment when it runs, and on the identifiers in scope for its generated
code.
It should act something like this:

(define-syntax (display-env stx)
(syntax-case stx ()
[(_)
(printf "Env: ~a" (local-environment))]))

> (lambda (x) (display-env) x)
Env: '(x)
#<procedure>
> (lambda (x) (let-syntax ([y (make-rename-transformer #'x)]) (display-env) y))
Env: '(y x)
#<procedure>

Presumably, the expander knows which identifiers are in scope, so I *ought* to
be able to get my hands on that set.

namespaces aren't the thing; they only give me access to the top-level
definitions, as far as I can tell.
I also want access to any lexical identifiers introduced by `λ` or `let` or
`let-syntaxes` or `let-values` etc.
But I want to be able to use them pretty much like namespaces: get the list of
symbols in scope, and get their values and identifiers.

Any one know how to do this?

--
William J. Bowman

[gfb]

Take a look at  syntax-debug-info , which you can see used in  https://github.com/AlexKnauth/debug/blob/master/debug/repl.rkt .

[William J. Bowman]

Excellent! Thanks.

> <https://docs.racket-lang.org/reference/stxops.html#(def._((quote._~23~25kernel)._syntax-debug-info))>

> , which you can see used in https://github.com/AlexKnauth/debug/blob/master/debug/repl.rkt
> .

> <https://github.com/AlexKnauth/debug/blob/master/debug/repl.rkt>
>
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