🚀 go-pugleaf

According to hoelzle@leland.Stanford.EDU (urs hoelzle):
>2.  Here's why you want at least some form of heterogeneous collections:
>	
>	type T = "some type"
>	type SubT = "subtype of T"
>
>	procedure someProc(c: List[T])
>
>    I think that you'll agree with me that you'd like to use someProc with
>    a Collection[SubT] ...

Actually, I don't agree.  And the burden of proof lay with the person
who says "X is necessary."

>    In a way, the problem exists because today's type systems are based on
>    what you *could* do to the list in someProc, not on what you actually do.

Without giving the compiler knowledge of the implementation of
someProc, that restriction is rather difficult to escape.

>3.  At least for rapid prototyping, your argument that "the type hierarchy
>    isn't perfect if this situation occurs" is invalid ...

Granted.  Always tradeoffs...  We here don't do rapid prototyping.
-- 
Chip Salzenberg at Teltronics/TCT     <chip@tct.uucp>, <uunet!pdn!tct!chip>
   "All this is conjecture of course, since I *only* post in the nude.
    Nothing comes between me and my t.b.  Nothing."   -- Bill Coderre