I'm having some difficulty using local-expand with regards to stop
lists. Here's what I'm trying:
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;; small-lang.rkt
#lang racket
(provide (except-out (all-from-out racket)
#%module-begin)
(rename-out [my-module-begin module-begin]))
(provide lift-to-toplevel)
;; lift-to-toplevel is meant to cooperate with module-begin.
(define-syntax (lift-to-toplevel stx)
(printf "lift to toplevel\n")
#'(void))
(define-syntax (my-module-begin stx)
(syntax-case stx ()
[(_ body ...)
(begin
(printf "Expanding...\n")
(let ([expanded-body
(local-expand #'(#%module-begin body ...)
'module-begin
(list #'lift-to-toplevel))])
(printf "expanded\n")
expanded-body))]))
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
I'd like local-expand not to immediately expand out the use of
lift-to-toplevel, but as far as I can tell, it's expanding
immediately. When I run a program like:
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
#lang s-exp "small-lang.rkt"
(printf "hello world\n")
(lift-to-toplevel (printf "ok!"))
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
I see the following content:
---------------------------------
Expanding...
lift to toplevel
expanded
hello world
---------------------------------
In which the first three lines are coming from compile-time, and I see
that my lift-to-toplevel macro is firing off, even though I placed it
in the stop-list of local-expand.
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