Re: covariant and contravariant rules


Subject: Re: covariant and contravariant rules
From: Vassily (vass@cs.washington.edu)
Date: Tue Dec 12 2000 - 07:11:03 PST


> Yes. I wanted the meaning of these terms in OOP in general.

Covariance for a type constructor t['a] generally means that
t1<=t2 implies t[t1]<=t[t2].

> I have also heard about 'Liskov's Substitution Principle.' Is it the
> same thing?

I think that's the notion aka "behavioral subtyping." I believe she has a
paper on this topic - check out the web.

Vass



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