[racket] Pattern matching define macro

> 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?


>
>>
>>
>>> 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.
>>>>>>
>>>>>
>>>>>
>>>>> ____________________
>>>>> Racket Users list:
>>>>> http://lists.racket-lang.org/users
>>>
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