* Using environment-bound? in macro definitions
@ 2017-01-02 23:30 Duncan Mak
2017-01-03 15:46 ` Per Bothner
0 siblings, 1 reply; 5+ messages in thread
From: Duncan Mak @ 2017-01-02 23:30 UTC (permalink / raw)
To: kawa mailing list
Hello,
Here's a stripped down version of two define-form macros that I'm working on:
(require 'syntax-utils)
(define-for-syntax known (list))
(define-syntax define-foo
(lambda (stx)
(syntax-case stx ()
((define-foo a)
(begin
(set! known (cons #'a known))
#'(define a (list)))))))
(define-syntax define-bar
(lambda (stx)
(syntax-case stx ()
((define-bar a n)
(if (environment-bound? (apply environment known) #'a)
#'(set! a (cons n a))
#'(begin
(define-foo a)
(set! a (cons n a))))))))
;; (1) should expand to (define x (list)) and store x in known
(define-foo x)
;; (2) should expand to (set! x (cons 1 x)) since x was previously
;; defined (i.e. can be found in known)
(define-bar x 1)
;; (3) should expand to (begin (define-foo y) (set! y (cons 2 y)))
;; because y is not previous defined
(define-bar y 2)
When I try to run it, I get
test.scm:29:1: evaluating syntax transformer 'define-bar' threw
gnu.text.SyntaxException: <unknown>: unknown library (x)
I must be doing something wrong, is this the right approach?
Thanks!
--
Duncan.
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: Using environment-bound? in macro definitions
2017-01-02 23:30 Using environment-bound? in macro definitions Duncan Mak
@ 2017-01-03 15:46 ` Per Bothner
2017-01-03 22:06 ` Duncan Mak
0 siblings, 1 reply; 5+ messages in thread
From: Per Bothner @ 2017-01-03 15:46 UTC (permalink / raw)
To: Duncan Mak, kawa mailing list
On 01/02/2017 03:29 PM, Duncan Mak wrote:
> (require 'syntax-utils)
> (define-for-syntax known (list))
>
> (define-syntax define-foo
> (lambda (stx)
> (syntax-case stx ()
> ((define-foo a)
> (begin
> (set! known (cons #'a known))
> #'(define a (list)))))))
>
> (define-syntax define-bar
> (lambda (stx)
> (syntax-case stx ()
> ((define-bar a n)
> (if (environment-bound? (apply environment known) #'a)
> #'(set! a (cons n a))
> #'(begin
> (define-foo a)
> (set! a (cons n a))))))))
>
> ;; (1) should expand to (define x (list)) and store x in known
> (define-foo x)
In other words, at this point:
(equal? known '(x))
test.scm:29:1: evaluating syntax transformer 'define-bar' threw
gnu.text.SyntaxException: <unknown>: unknown library (x)
That means you're evaluating (environment 'x).
The 'x is interpreted as an "environment specifier" - i.e. a library name,
and there is no such library (or class).
I think you misunderstand the 'environment' procedure. Check the Kawa and R7RS documentation.
What are you trying to do? Trying to dynamically build environment maps
is possible, but there isn't a Scheme API for it, and there are tricky interactions
between the dynamic top-level and the module-level lexical scope.
--
--Per Bothner
per@bothner.com http://per.bothner.com/
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: Using environment-bound? in macro definitions
2017-01-03 15:46 ` Per Bothner
@ 2017-01-03 22:06 ` Duncan Mak
2017-01-04 2:41 ` Duncan Mak
0 siblings, 1 reply; 5+ messages in thread
From: Duncan Mak @ 2017-01-03 22:06 UTC (permalink / raw)
To: Per Bothner; +Cc: kawa mailing list
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.
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: Using environment-bound? in macro definitions
2017-01-03 22:06 ` Duncan Mak
@ 2017-01-04 2:41 ` Duncan Mak
2017-01-04 4:33 ` Per Bothner
0 siblings, 1 reply; 5+ messages in thread
From: Duncan Mak @ 2017-01-04 2:41 UTC (permalink / raw)
To: Per Bothner; +Cc: kawa mailing list
Hello Per,
I just noticed that if I put my macros inside a R7RS define-library,
then it get these warnings:
(define-library (foo)
(export define-foo define-bar)
(import (kawa base) (kawa lib syntax))
(begin
(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))))))))))
(import (foo) (srfi 64))
(test-begin "t")
(define-foo x)
(test-equal '() x)
(define-bar x 1)
(test-equal '(1) x)
(test-end)
$ kawa test.scm
test.scm:13:14: warning - no declaration seen for known
test.scm:13:45: warning - no declaration seen for known
test.scm:21:27: warning - no declaration seen for known
%%%% Starting test t (Writing full log to "t.log")
# of expected passes 2
It'd be nice if there's a way to not have warnings show up.
Thanks again!
Duncan.
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: Using environment-bound? in macro definitions
2017-01-04 2:41 ` Duncan Mak
@ 2017-01-04 4:33 ` Per Bothner
0 siblings, 0 replies; 5+ messages in thread
From: Per Bothner @ 2017-01-04 4:33 UTC (permalink / raw)
To: Duncan Mak; +Cc: kawa mailing list
On 01/03/2017 06:40 PM, Duncan Mak wrote:
> $ kawa test.scm
>
> test.scm:13:14: warning - no declaration seen for known
> test.scm:13:45: warning - no declaration seen for known
> test.scm:21:27: warning - no declaration seen for known
>
> %%%% Starting test t (Writing full log to "t.log")
>
> # of expected passes 2
>
> It'd be nice if there's a way to not have warnings show up.
You can try compiling compiling with --no-warn-undefined-variable
or add:
(module-compile-options warn-undefined-variable: #f)
with-compile-options provides more localized control.
Perhaps this could be fixed in a cleaner way,
but I can't think of anything off-hand.
--
--Per Bothner
per@bothner.com http://per.bothner.com/
^ permalink raw reply [flat|nested] 5+ messages in thread
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2017-01-02 23:30 Using environment-bound? in macro definitions Duncan Mak
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2017-01-04 4:33 ` Per Bothner
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