Re: KAWA - define-generic

[Chris Bitmead <chris at bitmead dot com>]

Hmm, I read the doco on make-procedure through about 5 times, but I'm 
not sure I get it. The examples don't mention anything about types. I 
assume you are saying that...

(define Plus (make-procedure
 (lambda ((x :: <number>) (y :: <number>)) (+ x y))
 (lambda ((x :: <string>) (y :: <string>)) (string-append x y))))

should work, but then below you are implying it won't.

In any case, why must one specify all the methods up front? I thought 
that kinda the whole point  of generics was that you *don't* know up 
front what all the possible options might be.


Per Bothner wrote:


> Chris Bitmead wrote:
>
> > Is there something in Kawa like define-generic?
>
> There is 'make-procedure' (which is documented in the manual),
> and 'define-procedure' (which isn't documented but should be).
> Both of these require that all the methods be supplied in the
> call to 'make-procedure' or 'define-procedure'.
>
> It should be easy enough to implement define-generic and
> define-method, but I haven't.
>
> In any case, the support for generics needs a bit of work.
> The *intent* is that the following shuld work:
>
> (define-procedure Plus
>   (lambda ((x :: <number>) (y :: <number>)) (+ x y))
>   (lambda ((x :: <string>) (y :: <string>)) (string-append x y)))
>
> - but it doesn't.  I don't know when I can get it working.