DIP66 1.2 (Multiple) alias this. Continuation of work.

[Jeff Jones via Digitalmars-d]

On Sunday, 29 March 2015 at 17:34:21 UTC, IgorStepanov wrote:
> 3. is(T: B) should raise an error if there are many ways to 
> convert T to B.

I think this will cause future problems. How hard would it be to 
include at type algebra system? (being able to use &, |, etc on 
types... sort of Venn diagram'ish.

Also, is(T:B) should reflect what it means. Just because a dog 
can be classed many ways doesn't mean it's not a dog.

I realize that this makes things harder but is(T:B) raising an 
error if there are more than one conversion path just seems 
wrong. isonly(T:B) or whatever makes visual sense would be a 
better option IMO.