[racket] Pattern matching define macro

On Jul 12, 2014, at 10:17 PM, Alexander D. Knauth <alexander at knauth.org> wrote:

> 
> On Jul 12, 2014, at 6:43 PM, Brian Adkins <racketusers at lojic.com> wrote:
> 
>> I probably won't keep my defpat macro, at least not in its present form (for one, it only handles a single arg); there's probably a balance between being concise and being general/flexible.
> 
> Although define/match is definitely more powerful, if you want it, this would probably be a good version of what you want that would handle multiple arguments:  (I’ll reply again if I get one to work with optional and/or keyword-arguments)
> (define-syntax defpat
>  (syntax-rules ()
>    [(defpat (f arg-pat ...) body ...)
>     (defpat f (match-lambda** [(arg-pat ...) body ...]))]
>    [(defpat id expr)
>     (define id expr)]))

Ok I just made a version of defpat that can handle multiple arguments, optional arguments, keyword-arguments, and optional keyword-arguments.  
I also made a form called my-match-lambda that defpat uses to do this.  
https://github.com/AlexKnauth/defpat
Also to do this I had to make it so that you have to use square brackets to specify optional arguments, otherwise it couldn’t tell between an optional argument and a match pattern.