What is a type error?

[Joachim Durchholz]

Darren New schrieb:
> As far as I understand it, Eiffel compilers don't even make use of 
> postconditions to optimize code or eliminate run-time checks (like null 
> pointer testing).

That's correct.

I think a large part of the reasons why this isn't done is that Eiffel's 
semantics is (a) too complicated (it's an imperative language after 
all), and (b) not formalized, which makes it difficult to assess what 
optimizations are safe and what aren't.

(Reason (c) is that Eiffel compiler vendors don't have the manpower for 
this kind of work, mostly in quantity but also, to some degree, in 
quality: people with a solid language semantics background tend to be 
repelled by the language inventor's know-it-all deny-the-problems 
don't-bother-me-with-formalisms attitude. He still has moved the state 
of the art ahead - mostly by pointing out a certain class of problems in 
OO designs and explaining them lucidly, and proposing solutions that 
hold up better than average even if still fundamentally flawed.)

Regards,
Jo