I'm not sure why, but this works:
(unit
(import foo^)
(export bar^)
(+ foo bar)))
while this fails:
(define-syntax-rule (asyn body ...)
(unit
(import foo^)
(export bar^)
body ...))
(asyn (+ foo bar))
with the error "unit: undefined export" for any imported variables.
Somehow the (unit...) form is tied to the physical source location that it's
written in, so if a syntax transformer tries to introduce a unit syntax, when
the new syntax is used, the unit will consider the body spliced into it to be
outside of it, since the body has a different source location than the actual
definition of the syntax transformer itself.
Is there any way to work around this? I don't necessarily want to rely on
units, so I made a general syntax that would let me swap them out according to
my specific use of them, like (with-that-stuff etc ...) instead of (unit
(import that-stuff^) (export) etc ...). But that doesn't work, because for no
reason I can fathom, the etc... part gets evaluated before it gets spliced in,
even though define-syntax says it gets spliced in before evaluation.
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