[racket] Introductory talk on Contracts and Functional Contracts, with most examples in Racket

Hi Matthias

Thank-you for your sage advice:

On Tue, Sep 3, 2013 at 11:54 PM, Matthias Felleisen <matthias at ccs.neu.edu>
 wrote:

1. Always use contracts that cannot be expressed as types
> in an obvious type system.


I'll work on my examples.  I may also throw in an example in typed racket
to show the types and contracts working together.

2. Show a higher-order contract and flavors that push this
> idea hard. Consider using d/dx or indefinite adaptive integral ...
>

I'm a little bit wary of showing (only) a calculus-flavoured example
because I don't want to give the impression that  the higher-order
contracts are just for mathematical applications.

I'll try to come up with / search for a more "down to earth" example, but
if anyone has a practical, non-math, suggestion handy, please point me to
it!

I confess that as I have been learning about higher-order contracts I
wondered whether (instead) types + flat-contracts would suffice in practice
as a worse-is-better compromise.


> 3. For the smack-down, contracts tend to reveal some things that
> are "intensional" (part of the implementation).


Sounds bad for information hiding.  What's an example of this?


> Also, contracts
> can easily shift the algorithmic complexity if you're careless.
> See binary-search but impose sorted? as a predicate on the vector
> that flows into the function.


Makes sense.  I'll add it.

Good luck -- Matthias



Thanks!

Dan
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