"isDroppable" range trait for slicing to end

[Jonathan M Davis]

On Wednesday, October 31, 2012 11:37:13 monarch_dodra wrote:
> IMO, this makes a clean distinction between both "types" of
> slicing. An added bonus is that (for now) it also correctly
> supports finite RA ranges that don't define opDollar.

I don' think that such a distinction should be made at all. I think that all 
sliceable ranges should be required to implement opDollar. The problem is that 
it's unreasonable to require that when opDollar just got fixed, and arguably 
issue# 7177 should be implemented before it's reasonable to require it. But 
regardless, that means that creating a trait to test for opDollar working 
doesn't make sense. It would just have to be thrown away later.

> PS: Do we really have to force that infinite slice to be of a
> type of "take"? Does that mean we can't imagine an infinite range
> that defines it's own finite slice type?

I think that it's more valuable to make it consistent. What would a separate 
finite type even buy you? It would just be doing what take would do. I do kind 
of like the idea of just disallowing slicing without opDollar on infinite 
ranges though, in which case you'd have to use take yourself. I don't know 
what Andrei's take would be on that though.

- Jonathan M Davis