From: Jean Abou Samra <jean@abou-samra.fr>
To: Damien Mattei <damien.mattei@gmail.com>
Cc: Guile User <guile-user@gnu.org>
Subject: Re: macro definition for continue and break
Date: Sun, 4 Sep 2022 13:13:52 +0200 [thread overview]
Message-ID: <a56824fb-291f-ca3f-7f92-b17817c8a333@abou-samra.fr> (raw)
In-Reply-To: <CADEOadd2OAL-Z4o9AAR_mQ5_NSjCA1tVz5cDgeufVZ=ocAx0vQ@mail.gmail.com>
Hi,
Adding back the list in CC.
Le 04/09/2022 à 12:49, Damien Mattei a écrit :
> hello jean,
> yes (thank you for your help) i'm a sorcerer's apprentice that always
> push to later the understanding of literals in syntax-rules, but by
> instinct i finally succeed in making works the weird thing :-) , here
> is my macro definition now for a for with break and continue:
>
> (define-syntax for
>
> (lambda (stx)
> (syntax-case stx ()
> ((kwd (init test incrmt) body ...)
>
> (with-syntax
> ((BREAK (datum->syntax #'kwd 'break))
> (CONTINUE (datum->syntax #'kwd 'continue)))
>
> #`(call/cc
> (lambda (escape)
> (let-syntax
> ((BREAK (identifier-syntax (escape))))
> init
> (let loop ()
> (when test
>
> #,#'(call/cc
> (lambda (next)
> (let-syntax
> ((CONTINUE
> (identifier-syntax (next))))
> body ...)))
>
> incrmt
> (loop)))))))))))
>
> note the mysterious #,#' that save the day ;-)
For me, it works without it… ?
> and a few examples (in Scheme+)
>
> ;; scheme@(guile-user)> (for ({i <+ 0} {i < 5} {i <- {i + 1}}) {x <+
> 7} (display x) (newline) (break))
> ;; 7
> ;; scheme@(guile-user)> (for ({i <+ 0} {i < 5} {i <- {i + 1}}) {x <+
> 7} (continue) (display x) (newline) (break))
> ;; scheme@(guile-user)>
>
> ;; (for ({k <+ 0} {k < 3} {k <- {k + 1}})
> ;; (display k)
> ;; (newline)
> ;; (for ({i <+ 0} {i < 5} {i <- {i + 1}}) {x <+ 7}
> ;; (display x)
> ;; (newline)
> ;; (break))
> ;; (newline))
>
> ;; 0
> ;; 7
>
> ;; 1
> ;; 7
>
> ;; 2
> ;; 7
>
> ;; (for ({k <+ 0} {k < 3} {k <- {k + 1}})
> ;; (display k)
> ;; (newline)
> ;; (continue)
> ;; (for ({i <+ 0} {i < 5} {i <- {i + 1}}) {x <+ 7}
> ;; (display x)
> ;; (newline)
> ;; (break))
> ;; (newline))
>
> ;; 0
> ;; 1
> ;; 2
>
> https://github.com/damien-mattei/library-FunctProg/blob/master/for-next-step.scm
>
> it also works with imbricated loops in a natural way (but other
> interpretation and implementation could be done , C act like this ,i
> think)
> but if it could be coded better i will use a better version
Yes, it can be done better; see my reply on the other thread.
Best,
Jean
next prev parent reply other threads:[~2022-09-04 11:13 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-09-04 8:19 macro definition for continue and break Damien Mattei
2022-09-04 10:08 ` Jean Abou Samra
[not found] ` <CADEOadd2OAL-Z4o9AAR_mQ5_NSjCA1tVz5cDgeufVZ=ocAx0vQ@mail.gmail.com>
2022-09-04 11:13 ` Jean Abou Samra [this message]
2022-09-12 19:19 ` Linus Björnstam
2022-09-12 20:57 ` Loop macros (was: Re: macro definition for continue and break) Maxime Devos
2022-09-12 21:09 ` Linus Björnstam
2022-09-13 14:25 ` Damien Mattei
2022-09-13 14:28 ` Maxime Devos
2022-09-14 15:56 ` Damien Mattei
2022-09-13 14:16 ` macro definition for continue and break Damien Mattei
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