Extension methods and API evolution

[Paulo Levi]

I think mr. Ahe is right and callee site extension methods are best. In fact
if they can be hidden or only usable by the jdk people, i would like them to
be unusable by others, since traits appear to be the general solution (nigh
on replacing the concept of interface), and can be added later, fully
replacing this compiler trick.

I believe this is fundamental to allow the jdk libraries to evolve, code in
the interfaces non-withstanding, unless you want to go the .Net path with
breaking binary compatibility. Otherwise you invite extreme fragmentation,
and more so that you're going to add closures. I for one would convert my
projects in a snap for a collections library that had reduce or map, if the
readable possibility for that was there, and the jdk didn't add them. I
don't think i'm alone in this.