[racket] Pattern matching define macro

On Jul 15, 2014, at 6:37 PM, Stephen Chang <stchang at ccs.neu.edu> wrote:

>> Also I was thinking I could use it to make gen-bind expanders for match-patterns if I need them.
> 
> There's a define-match-bind that consumes a match pattern and defines
> a $-prefixed name for that specific pattern that can be used in
> gen-bind positions. Does that help?

Oh.  When I saw that I thought it was just for structs.  

> 
> 
>> 
>>> 
>>> 
>>>> And is there some kind of "generic-bind/renamed” module or something that provides everything from generic-bind except without the ~ in front?
>>> 
>>> Good idea. Yes, in hindsight my choice of names was probably
>>> suboptimal. I've incorporated your suggestion so now you can do
>>> (require generic-bind/as-rkt-names), which drops all ~-prefixes
>>> (except for ~vs). Thanks!
>>> 
>>> 
>>>> 
>>>> 
>>>> On Jul 15, 2014, at 3:02 PM, Stephen Chang <stchang at ccs.neu.edu> wrote:
>>>> 
>>>>>> I just found this, which has a lot of forms for just about everything I can think of (and more) that support things like match-patterns:
>>>>>> https://github.com/stchang/generic-bind
>>>>>> 
>>>>>> I haven’t tried it yet, but It looks pretty amazing.
>>>>>> 
>>>>>> It probably has everything you want.
>>>>> 
>>>>> Thanks for the kind words. :)
>>>>> 
>>>>> This was an experiment that tried to address a few questions that
>>>>> repeatedly get asked on the mailing list:
>>>>> 
>>>>> 1) that you can't destructure data structures at the binding site, and
>>>>> 2) that you need to manually define many different versions of each
>>>>> binding construct (eg define, match-define, match-define-values, etc),
>>>>> which inevitably means that some binding forms don't exist (eg
>>>>> match-for/X forms)
>>>>> 
>>>>> Something like the expressivity problem for binding forms.
>>>>> 
>>>>> I tried to implement one "generic" version of each binding form that
>>>>> would accept many different "binding instances", so every binding form
>>>>> would be extensible by implementing the appropriate instance (eg, a
>>>>> matching instance, a values instance)
>>>>> 
>>>>> Every Racket binding form should have a ~-prefixed version in my
>>>>> library and my version should work as a drop-in replacement for its
>>>>> Racket counterpart if you want to try it out.
>>>>> 
>>>>> Here's a link to the docs if you're interested in reading more:
>>>>> http://stchang.github.io/generic-bind/generic-bind.html
>>>>> 
>>>>> (You can tell that it hasn't been updated in a while from the old css.)
>>>>> 
>>>>> Caveat: my macro-fu hasn't quite reached expert level so I'd love for
>>>>> anyone to tell me where my code is bad.
>>>>> 
>>>>> That being said, I ran a large part of the Racket test suite using my
>>>>> binding forms instead of the Racket ones so they should be usable in
>>>>> most scenarios.
>>>>> 
>>>>> 
>>>>> 
>>>>> 
>>>>> 
>>>>> 
>>>>> 
>>>>>> 
>>>>>> On Jul 13, 2014, at 12:41 AM, Alexander D. Knauth <alexander at knauth.org> wrote:
>>>>>> 
>>>>>>> 
>>>>>>> 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.
>>>>>>> 
>>>>>> 
>>>>>> 
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>>>>>> http://lists.racket-lang.org/users
>>>> 
>>