On Aug 24, 2014, at 2:09 PM, Matthias Felleisen <[email protected]> wrote:
> Before you make fondue, ask. As you can see, people answer and answer
> quickly. Indeed, Robby added an example to the Guide as he responded and
> pushed it out into the repo. The next release will have an example due to
> your posts. Thanks!
>
> Having said that, Racket is created by people who focus on systematic design
> of software. The contract system is an example of this;
>
> -- it serves the purpose of creating software systematically (continuing the
> so-called Design by Contract line of work)
> -- it itself is developed systematically with inquires into the semantics of
> contracts because we took contracts way beyond the primitive notion from the
> 1980s and 1990s.
>
> But, the existence of ->i and ->d should give you a hint that we occasionally
> make mistakes and we try to correct them without modifying existing code. ->d
> is mostly okay, but ->i is better. When Robby created ->i, he also used his
> experience with ->d to force programmers to list dependency variables
> explicitly. That's why you have to say "(lst)", for example. In addition, the
> language grows and with it, we have to grow the contract system. Keyword
> arguments is an example of that kind.
>
> As for the philosophy behind our contract system, I think the guide's opening
> section on boundaries brings across the idea that separates our contracts
> from old-style stuff. It may not become immediately clear, but when you
> program with contracts for a while, you will appreciate it.
Wow! I am increasingly appreciating this approach (along with Racket’s
systematic approach to design).
I’m slowly converting my modules over to use contract-out and the ->i form
makes it easy to see at a glance what the domains and ranges are, and I’m
thinking the notation might be useful in the function definition’s comments as
well. Is there a way to integrate unit testing into this approach? The (module+
test …) unit testing I’ve been doing is within the boundary of the mode and I
wonder if there isn’t a way to simply move those test cases into another module
(within the same file) and require it into the (module+ test …) form?
-Kevin
____________________
Racket Users list:
http://lists.racket-lang.org/users
