[racket-dev] Providing macro definitions for BSL programs

I think it's time to write a guide on how to write teachpacks. 
Robby and I are no longer alone. -- Matthias



On Sep 4, 2010, at 6:29 PM, Matthew Flatt wrote:

> See `first-order->higher-order'.
> 
> At Sat, 4 Sep 2010 17:00:52 -0400, Nadeem Abdul Hamid wrote:
>> Ah, thank you. Now, how about this definition:
>> 
>> (define-syntax (my-macro stx)
>>  (syntax-case stx (->)
>>    [(_ (func arg ...) -> rslt)
>>     #`(length (cons func (list arg ...)))]))
>> (provide my-macro ->)
>> 
>> i.e. my macro takes the function name, bundles in up in a structure
>> (here I just used "cons") and then maybe passes it off to something
>> else for processing (here I just used "length" for illustration).
>> 
>> Now, doing something like this in the BSL file:
>>   (my-macro (reward 3) -> "bronze")
>> 
>> produces:
>>  reward: this is a procedure, so it must be applied to arguments
>> (which requires using a parenthesis before the name)
>> 
>> 
>> 
>> 
>> 
>> On Sat, Sep 4, 2010 at 4:42 PM, Matthias Felleisen <matthias at ccs.neu.edu> 
>> wrote:
>>> 
>>> You need to define and export -> . Otherwise students don't have access to 
>> the specific -> in your macro.
>>> 
>>> BTW, injecting macros into *sl languages demands a lot of error checking 
>> because novices are easily confused.
>>> 
>>> 
>>> 
>>> 
>>> On Sep 4, 2010, at 4:37 PM, Nadeem Abdul Hamid wrote:
>>> 
>>>> Suppose I make a "teachpack" that defines a macro:
>>>> 
>>>> #lang racket
>>>> ...
>>>> (define-syntax (my-macro stx)
>>>>  (syntax-case stx (->)
>>>>    [(_ (func arg ...) -> rslt)
>>>>     #`(check-expect (func arg ...) rslt)]))
>>>> (my-macro (+ 4 5) -> 10)
>>>> (test)
>>>> (provide my-macro)
>>>> 
>>>> Running this file works fine.
>>>> 
>>>> Now, how exactly do I make this macro available to programs written in
>>>> Beginning/Intermediate Student? Opening up a file in BSL level and
>>>> typing:
>>>>  (require "my-macro.rkt")
>>>>  (my-macro (+ 4 5) -> 9)
>>>> gives the error:
>>>>  my-macro: bad syntax
>>>> 
>>>> This macro is a simplification of the real thing I'm working on, but
>>>> note that the arguments to this macro include name(s) of functions
>>>> defined in the BSL file. I though of maybe using
>>>> provide-higher-order-primitive, but it doesn't seem to work either.
>>>> 
>>>> --- nadeem
>>>> _________________________________________________
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>>> 
>>> 
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