Checking if a string is null

[Manfred Nowak]

Bruno Medeiros wrote

> (What made you do that in the first place?)

Because arrays should approximately form a mathematical Kleene Algebra 
at the semantical level. These have two different neutral elements 0 
and 1, so that concatenation and 1 are required to form a monoid.


> However at the semantic level, they *are* the same abstract objects
> (which is what opEquals checks)

And in D definitions as well as implementations check the neutral 
elements 0 and 1 for arrays at least sometimes to be equal.


> Yes, "there is no identity preserving element for arrays under the
> concatenation operation", and that's really no problem whatsoever.
> (Do you even know of a non-value type that has identity preserving
> element with regards to any operation?)

This probably will boil up by the missing definition for an equivalence 
relation on types, which defines one equivalence class that holds all 
the "non-value type"s.

-manfred