[E-Lang] Immutable map operations

[Tyler Close]

Dean wrote:
> In E, there is no
> contract for "&",
> it's just a string.  There's no place to document that the
> associated
> implementation is associative or commutative or supports basic
> set-theoretic axioms.  But those guarantees are important,
> and I would much
> rather have assurance that they held for sets, regions, functions,
> bitvectors, etc. than have other semantics wedged into them
> to leverage the
> syntax.

Pursuant to my request for some code examples of "surprising
operations", I think E should document the contract for the various
operators by creating a test suite of programs that check the various
axioms that an operator implementation must obey. Once such a test
suite has been agreed on, it will be possible for a library designer
to get a definitive and objective answer as to whether their use of
the operator expansions is "good" or "bad" design. The prominent
existence of this test suite in the E download should be enough to
radically reduce the occurence of "wanton abuse of operator
expansions" that language like C++ suffer from.

Tyler