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Re: [Scheme-reports] Formal Response #382: Allow "if" to accept arbitrarily many if-then pairs
On Thu, 11 Oct 2012 22:21:05 -0400, John Boyle
> Aaron, I can't get your example to run.
Sorry, that was a quick one-off and not intended to be runnable (the
export list is completely
invalid for one). Here's an example that you can actually cut and paste as
a series of libraries.
(import (rename (rnrs) (if %if)))
[(_) (%if #f #t)]
[(_ t c r ...) (%if t c (if r ...))])))
(import (except (rnrs) if) (for (extended-if) run expand))
(let ([x (cadr (syntax->datum x))])
(if x 42 (not x) 24))))
(define result (list (test #t) (test #f))))
Notice that you only need the explicit FOR when you are dealing with
explicit phasing systems like Racket. On systems like Chez or
Vicare/Ikarus, you should be able to just specify the (extended-if)
library and have things work.
Aaron W. Hsu | arcfide@x | http://www.sacrideo.us
Programming is just another word for the Lost Art of Thinking.
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