[plt-scheme] (provide ...) question

Sorry, yes.


On May 18, 2010, at 10:30 AM, Todd O'Bryan wrote:

> How would I do that? It looks like if I use
>
> (provide/contract (struct city-line) ...)
>
> there's no way to except the make-city-line constructor, and
> with-contract doesn't have a struct version, so I'm afraid I'd have to
> provide explicit contracts for every function the define-struct
> creates.
>
> Sorry if I'm being dense,
> Todd
>
> On Tue, May 18, 2010 at 10:11 AM, Matthias Felleisen
> <matthias at ccs.neu.edu> wrote:
>>
>> I think this is a (known) bug in define-struct/contract.
>>
>> Also consider exporting a contracted structure instead of defining  
>> a struct
>> with a contract. Slightly different meanings but the former appears  
>> to be
>> what you want.
>>
>>
>> On May 18, 2010, at 10:03 AM, Todd O'Bryan wrote:
>>
>>> Whoops. I tried to simplify the example, and simplified it to the
>>> point where it works. It seems that the problem is actually when I  
>>> try
>>> to use define-struct/contract:
>>>
>>> #lang scheme
>>> (provide (except-out (struct-out city-line)
>>>                   make-city-line)
>>>       (rename-out [better-make-city-line make-city-line]))
>>>
>>> (define-struct/contract city-line
>>>  ([city string?]
>>>  [state #px"[A-Z]{2}"]
>>>  [zip #px"\\d{5}"]
>>>  [zip+4 #px"\\d{4}"]))
>>>
>>> (define better-make-city-line
>>> (case-lambda
>>>  [(city state zip zip+4)
>>>   (make-city-line city state zip zip+4)]
>>>  [(city state zip)
>>>   (make-city-line city state zip "")]))
>>>
>>> causes the error:
>>>
>>> except-out: identifier to remove `make-city-line' not included in
>>> nested provide spec in: (struct-out city-line)
>>>
>>> Sorry for not checking my example!
>>> Todd
>>>
>>> On Tue, May 18, 2010 at 9:43 AM, Matthias Felleisen
>>> <matthias at ccs.neu.edu> wrote:
>>>>
>>>> In what way doesn't this do "it"?
>>>>
>>>>
>>>> On May 18, 2010, at 8:44 AM, Todd O'Bryan wrote:
>>>>
>>>>> I have a struct that I'd like to provide from a module, but I'd  
>>>>> like
>>>>> to provide a different constructor to modules that require it.  
>>>>> Here's
>>>>> a simple example:
>>>>>
>>>>> (define-struct city-line (city state zip zip+4))
>>>>>
>>>>> (define better-make-city-line
>>>>>  (case-lambda
>>>>>  [(city state zip zip+4)
>>>>>   (make-city-line city state zip zip+4)]
>>>>>  [(city state zip)
>>>>>   (make-city-line city state zip "")]))
>>>>>
>>>>> I tried this:
>>>>>
>>>>> (provide (except-out (struct-out city-line)
>>>>>                   make-city-line)
>>>>>       (rename-out [better-make-city-line make-city-line]))
>>>>>
>>>>> but that doesn't seem to do it.
>>>>>
>>>>> Is there a way to do such a thing? Am I close?
>>>>>
>>>>> Thanks,
>>>>> Todd
>>>>> _________________________________________________
>>>>>  For list-related administrative tasks:
>>>>>  http://list.cs.brown.edu/mailman/listinfo/plt-scheme
>>>>
>>>>
>>
>>