[racket] Contracts and submodules

Similar mode here. 

My "list of things to improve my programming by programming" 
goes into a project folder called Lib/ . When I don't have
time, I write down a design and GTD. When I have breathing
space, I return and invest time in the 'todo' list. It almost
always pays off soon after I invest time. 

-- Matthias




On Mar 5, 2013, at 4:59 PM, Greg Hendershott wrote:

> Thank you for the "de-clutter" strategies. I realized I could do
> something of this sort. One of the things I love the most about Racket
> is the ability to do this. On the other hand sometimes that capability
> can be distracting for me.
> 
> For example lately I've wanted to focus more on programming in Racket
> -- as opposed to programming my programming in Racket. Get some more
> projects done.
> 
> I seem to have a daemon running that tries to notice how/why I got
> confused, created a bug, and so on, and ponder how to avoid that next
> time. But sometimes that daemon needs to dump its observations in a
> buffer for me to consider later, as opposed to preempting my main
> thread. So the last few weeks I've been more GTD, less meta. Ergo some
> grumbly.
> 
> Another daemon I seem to have running, is one calculating what might
> help Racket gain greater acceptance "in industry". The constant
> innovation is wonderful -- who can complain about better options for
> things like modules, tests, correctness, and more. At certain stages
> in the evolution it can perhaps result in a slightly unclear story
> about what are the best or preferred practices. Particularly for folks
> jumping in new to Racket (but not necessarily to programming in
> general).
> 
> Anyway, enough talk of my personal daemons. :)
> 
> Seriously thanks again for your feedback and ideas.
> 
> On Tue, Mar 5, 2013 at 9:59 AM, Matthias Felleisen <matthias at ccs.neu.edu> 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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