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Re: no class-of ?
On a somewhat related note, is there a way to define a macro that can
determine the type of an expression at macro expansion time, without
actually evaluating the expression?
I'd like to be able to do something along the lines of:
(define-syntax (ensure-boolean form)
(syntax-case form ()
((_ expr)
(let ((the-type (???? #'expr)))
(cond ((eq? the-type boolean) #'expr)
((eq? the-type void) #'(begin expr #t))
((eq? the-type int) #'(= expr 0))
(else (syntax-error "unsupported expression type")))))))
to be used as in:
(define (f x::double) ::boolean ...)
(define (g) ::int ...)
(define (h) ::void ...)
(list (ensure-boolean (let ((x 1.0)) (f x)))
(ensure-boolean (g))
(ensure-boolean (h)))
=>
(list (let ((x 1.0)) (f x))
(= (g) 0)
(begin (h) #t))
> On Sep 21, 2017, at 11:23 AM, Per Bothner <per@bothner.com> wrote:
>
> On 09/21/2017 04:11 AM, Sonny To wrote:
>> there seems to be class-of function to get the type of the r-value of a symbol.
>
> You can use the Java getClass method:
> (VALUE:getClass)
> or:
> (invoke VALUE 'getClass)
> or the "property" short-hand:
> VALUE:class
>
>> I'm not familiar with with the standard libraries of scheme and i'm
>> googling to get documentation and find various scheme documentation
>> from mit-scheme/racket/guile but are not available in kawa.
>> Is there a place where I can find a list of functions built into kawa?
>
> The Kawa manual attempts to document all the Kawa functions.
> In the past I concentrated on documenting only Kawa extensions/differences
> from standard Scheme (so you needed to also have a copy of R5RS/R7RS), but
> I'm gradually making the Kawa manual more complete and self-contained.
> (There may still be some R7RS procedures missing, though.)
>
> There are also some implemented SRFIs, not all of which are fully documented
> in the Kawa manual. See:
> https://www.gnu.org/software/kawa/Implemented-SRFIs.html
>
> Of course all of the Java APIs are always available, by using Java
> method calls:
> https://docs.oracle.com/javase/8/docs/api/overview-summary.html
> That is where you will find getClass documented:
> https://docs.oracle.com/javase/8/docs/api/java/lang/Object.html#getClass--
> (the final '--' in the URL seems to be needed.)
> --
> --Per Bothner
> per@bothner.com http://per.bothner.com/
--
Jamison Hope
The PTR Group
www.theptrgroup.com