[racket] style guide, was Re: Contracts and submodules

P.S. I have re-written chapter 3 of the style guide in particular 3.3 and 3.6 to add your idea: 

 http://www.ccs.neu.edu/home/matthias/Style/style/Units_of_Code.html



On Mar 5, 2013, at 9:59 AM, Matthias Felleisen wrote:

> 
> 1. Clutter removal is built into Racket: 
> 
> (define-syntax (interface stx)
>  (syntax-case stx (subject-to)
>    [(interface name clauses ...)
>     ;; ==> 
>     .. (provide (contract-out ..) ..) ..]))
> 
> The above macro has become a standard in my recent projects where I place it into my ./Lib/contract.rkt library. It is part of an effort to develop a header-file style for Racket. And it is an effort to supply a way to selectively check contracts. [More soon. It is NOT about turning contracts off.]
> 
> 2. Contract test issue acknowledged. I have run into this problem too during my recent construction of a game program. My work-around 
> 
> 3. Clutter removal is built into Racket: 
> 
> #lang racket
> 
> #lang racket
> 
> (define-syntax-rule
>  (tmod def-or-exp ...)
>  (module* test racket
>    (require rackunit (submod ".."))
>    (check-equal? 1 1)
>    def-or-exp ...))
> 
> ;; -----------------------------------------
> 
> (provide
> (contract-out
>  (f (-> integer? integer?))))
> 
> (define (f x) x)
> 
> (tmod (check-equal? (f 2) 2)
>      (check-equal? (f 3) 2))
> 
> Consider adding the above module to your ./Lib/contract.rkt library. 
> 
> 
> 
> 
> 
> 
> On Mar 5, 2013, at 8:39 AM, Greg Hendershott wrote:
> 
>> Not to flog this, but:
>> 
>> Lately I've been trying to be a good little doobie and use `(provide
>> (contract-out))` instead of `define/contract`. Although it's more
>> typing/clutter, grumble grumble, I've been getting used to it.
>> 
>> Unfortunately I discovered one gotcha: Using (module+ test <rackunit
>> tests>) means that the test bypasses the contract -- because it's a
>> submodule, and the contract is on the module boundary. So my unit
>> tests weren't exercising and validating the contract. I missed a buggy
>> contract this way.
>> 
>> In hindsight this is all perfectly obvious. Just not from the guide.
>> To be fair using submodules for tests is a relatively recent practice
>> in Racket. But I wanted to point out the interaction in case it helps
>> anyone else who is trying to use module contracts and do unit tests
>> following the curent examples.
>> 
>> One way to avoid this problem is instead of module+ use module*:
>> 
>> (module* test racket ;; To test module-boundary contracts, must use
>>                      ;; module* and (require (submod "..")).
>>   (require (submod ".."))
>>   ... check check check ...
>>   )
>> 
>> Of course this adds even more "clutter", but it works.
>> 
>> On Thu, Dec 27, 2012 at 3:31 PM, Matthias Felleisen
>> <matthias at ccs.neu.edu> wrote:
>>> 
>>> I have added a note on this issue to the Style issue; see section 3.6. Strictly speaking, this prose probably belongs into the Contract guide. -- Matthias
>>> 
>>> 
>>> 
>>> On Nov 30, 2012, at 5:17 PM, Ryan Culpepper wrote:
>>> 
>>>> You can have mutually recursive functions with define/contract, but you can't with submodules.
>>>> 
>>>> Ryan
>>>> 
>>>> On 11/30/2012 05:04 PM, Ray Racine wrote:
>>>>> Why not make this explicit by deprecating define/contract and support
>>>>> this use case with a submodule.  They lightweight enough and makes
>>>>> boundary demarcations consistent, explicit and simple.  Module -> boundary.
>>>>> 
>>>>> On Nov 30, 2012 12:05 PM, "Matthias Felleisen" <matthias at ccs.neu.edu
>>>>> <mailto:matthias at ccs.neu.edu>> wrote:
>>>>> 
>>>>> 
>>>>>  On Nov 30, 2012, at 10:15 AM, Greg Hendershott wrote:
>>>>> 
>>>>>>> This is a complete misunderstanding.
>>>>>> 
>>>>>> Sometimes I feel like a kid in the room while the adults are talking.
>>>>>> When it comes to contracts, I have to stipulate that most of you are
>>>>>> smarter than me and have thought about this longer than me.
>>>>> 
>>>>> 
>>>>>  Apologies. My opening wasn't meant to say "I am smarter" but I wanted
>>>>>  to send a strong message about define/contract. It really introduces a
>>>>>  boundary and in some strange sense your (possibly misleading)
>>>>>  microbenchmark
>>>>>  exposes this constraint too.
>>>>> 
>>>>> 
>>>>> 
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>>>>> 
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