On Tuesday, March 11, 2003, at 10:56 PM, Richard A. O'Keefe wrote:

> Roel Wuyts <roel.wuyts at iam.unibe.ch> wrote:
> 	Let me rephrase:  I was talking about OO static typing systems.
> 	Type systems for OO systems I know of are now looking more into
> 	typing generics, but are not quite there yet (in my opinion).
> 	Do you have some pointers to a complete OO language that has no
> 	typecasts?
>
> Well, much depends on what you think a typecast is.
> Does Eiffel's "conditional assignment" count?
> In Eiffel,
> 	lhs ?= rhs
> has the effect that if the run-time type of rhs is compatible with the
> compile-time type of lhs, then the value of rhs is assigned to lhs,
> otherwise lhs becomes a Void reference.  Note that this cannot be used
> to subvert the type system; Eiffel has no features for that.  The value
> of lhs is _always_ appropriate for its declared type.
>
> 	but extended records are not enough; they don't provide
> 	you full objects I thought. Do they have late binding of self? I
> 	thought they only provided a form of data sharing.
>
> I have no idea what you mean by data sharing, and I did not write
> "extenDED records" but "extenSIBLE records".  More precisely, a value
> of one record type conforms to another record type if each of the
> fields in the second type appears in the first and the corresponding
> field types match up right.  Of course self is late bound, why wouldn't
> it be?

Because in object-based languages (as opposed to object-oriented) it is 
not. See VisualBasic before they were really OO. You had inheritance as 
far as data was concerned, but you could not override methods (no late 
binding of self).

I don't know O'CAML (well, I know the name), that is why I asked... but 
I'll read the manual.

> Do read the O'CAML manual.  I don't really like O'CAML syntax
> much (it's several functional language design generations out of date),
> but it's a powerful system and regularly wins speed races for compiled 
> code.
>
>
Roel Wuyts                                                   Software 
Composition Group
roel.wuyts at iam.unibe.ch                       University of Bern, 
Switzerland
http://www.iam.unibe.ch/~wuyts/
Board Member of the European Smalltalk User Group: www.esug.org