Htdp: Contracts

[Brent Fulgham <brent.fulgham@xpsystems.com>]

While glancing through the "How to design programs" web-book, I noticed
the frequent use of a "Contract" notation at the top of code snippets.
(I also have seen this in some of the Scheme code linked from elsewhere
on the PLT site).

Does notation of the form:

Type Type -> Type

or

Type Type -> Unit

Indicate any future plans for an Eiffel-style design-by-contract
mechanism within MrEd and friends?

I think the functional approach to programming greatly reduces the
incidence of some forms of contract violation, but a good mechanism
of establishing pre/post conditions would be a pretty useful tool.

(Of course, there would be far less need to label invariants since
most Scheme values are by definition invariant :-)  The use of
the "bang" notation does help warn you when something might be
changed unexpectedly...)

-Brent