On Wed, 09 Nov 2022, Damien Mattei <damien.mat...@gmail.com> wrote:
> but in the general case , i want a macro that can do it on any function
> (i'm not sure it can be done because the continuation have to be captured
> just before the call to the function and be inlined at the good
> place....)
I'm not aware of any control mechanism that are implicit in Guile. You
almost always have to deal with a continuation object. However, nothing
prevent you to invent your own control flow wrapper.
For example:
--8<---------------cut here---------------start------------->8---
(define my-prompt (make-prompt-tag))
(define-syntax-rule (return-now x)
(abort-to-prompt my-prompt x))
(define (wrap-this procedure)
(let ((inside? #f))
(lambda args
(if inside?
(apply procedure args)
(begin
(set! inside? #t)
(let ((ret
(call-with-prompt my-prompt
(lambda ()
(apply procedure args))
(lambda (_ x)
x))))
(set! inside? #f)
ret))))))
(define-syntax define-interruptible
(syntax-rules ()
((_ (name formals ...) body ...)
(define name
(wrap-this
(lambda (formals ...) body ...))))))
(define-interruptible (foo n)
(cond
((= n 0) 'end0)
((= n 7) (return-now 'end7))
(else
(cons n (foo (1- n))))))
(pk (foo 5))
(pk (foo 10))
--8<---------------cut here---------------end--------------->8---
There's probably other way of doing so that I'm not aware of.
--
Olivier Dion
oldiob.dev
