From: Duncan Mak <duncanmak@gmail.com>
To: Per Bothner <per@bothner.com>
Cc: kawa mailing list <kawa@sourceware.org>
Subject: Re: Using environment-bound? in macro definitions
Date: Tue, 03 Jan 2017 22:06:00 -0000 [thread overview]
Message-ID: <CABgWrqp1LO93SUOR0H4_zQTv4KbcxrfLbN4HWQjoJv2jxBiUvg@mail.gmail.com> (raw)
In-Reply-To: <f506008b-51b8-5d42-aaa0-49eba2a5d7a3@bothner.com>
Hello Per,
Ah! You're totally right. I thought I'll need to use the environment
instance but if I just keep a data structure (known) at syntax time, I
won't need to deal with environments at all, because 'known' will be
the environment (for my purposes).
This is the working code:
(define-for-syntax known (list))
(define-syntax define-foo
(lambda (stx)
(syntax-case stx ()
((define-foo a)
(begin
(set! known (cons (list #'a 0) known))
#'(define a (list)))))))
(define-syntax define-bar
(lambda (stx)
(syntax-case stx ()
((define-bar a n)
(identifier? #'a)
(if (assoc #'a known)
#'(set! a (cons n a))
#'(begin
(define-foo a)
(set! a (cons (list n 0) a))))))))
(define-foo x)
(display x) (newline) ;; prints ()
(define-bar x 1)
(display x) (newline) ;; prints (1)
Thanks!
Duncan.
next prev parent reply other threads:[~2017-01-03 22:06 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-01-02 23:30 Duncan Mak
2017-01-03 15:46 ` Per Bothner
2017-01-03 22:06 ` Duncan Mak [this message]
2017-01-04 2:41 ` Duncan Mak
2017-01-04 4:33 ` Per Bothner
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