Why no multiple-dispatch?

[via Digitalmars-d-learn]

On Monday, 25 August 2014 at 07:36:22 UTC, Idan Arye wrote:
> Are you suggesting the compiler will try to resolve the 
> polymorphism at compile-time, looking at all possible paths 
> that lead to a function call to check all possible runtime 
> values it's object arguments can get?

I've argued for whole program analysis before and this is another 
example where it would be useful :-). When you have figured out 
the worst-case use pattern you can either make one function 
virtual and then inline the others as a switch or you can create 
class-ids that can be hashed perfectly to an array of function 
pointers.

However, why do you want multiple dispatch? I cannot think of any 
application level use scenario where you have two class 
hierarchies that you have no control over. So I don't really see 
the value of multiple dispatch in a system level programming 
language. Perhaps if you want to use D for an application level 
DSL? What are the use scenarios you guys have experience with 
where multiple dispatch was indispensable?

Ola.