On Tue, 24 Feb 2009, Sam TH wrote:
On Tue, Feb 24, 2009 at 6:03 PM, John Cowan <[email protected]> wrote:
Tangent: Can someone explain to me what the merit is in being able to
reference macros before they are defined in *any* context? Perhaps there
is one, but I don't see it.
If you define a macro to that simulates a value definition form with a
macro definition form (this is what my `define-inline' example does,
using `syntax-rules'), then you would probably want to have mutual
recursion among these definitions be possible.
This might be a bit of expressiveness in the macro system that could
be given up at the REPL, though.
Well, not that much expressiveness. You can fix your example
(import (rnrs))
(define-syntax definline
(syntax-rules ()
[(_ (n . args) body)
(define-syntax n
(syntax-rules ()
[(_ . args) (lambda () body)]))]))
(definline (even-printer n) (if (even? n) ((print-even n)) #f))
(define p (even-printer 12))
(definline (print-even n) (begin (display n) (display " is even")))
to be workable in a REPL by simply exchanging the last two lines.
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