Immutable map - put / add

Hi all,

What is the shortest/best way of creating an immutable map from another immutable map plus a new element possibly overriding an element?
Is there a reason why the + - operators are not supported?


Side note: those are not immutable maps, but read-only maps. They may be mutated elswhere, but the reference we are holding does not permit mutation.

Ah yes indeed, read-only is a better expression.

Meanwhile, I have registered a feature request for this: