Side-effect free containers for E

[Marc Stiegler]

> Redesign Conservatism.  E has spent some time maturing.  Much less than
many
> languages, but enough not to be sneezed at.  It has users and an installed
> base of working production software.  Ok, two programs, but one (EDesk) is
> substantial.  It has a community of interest (you guys), the people who
> should be our early adopters, mostly *not* investing their time in
actually
> using the language, perhaps because of fear that it "isn't stable yet".
> Those familiar with my history may even have an exaggerated degree of this
> fear.  The current discussion may have already irreparably damaged any
> growing confidence you guys may have in E's upcoming stability.

This is an important point, and forces me to back slightly away from my
earlier proposal of "make immutables stronger and mutables weaker". To
encourage confidence in stability, you want to maintain upward compatibility
unless the reasons are overwhelmingly compelling, so I now recommend leaving
mutables alone.

If we accept that we're going to leave the mutables alone, upgrading the
immutables (which I think is a good idea, indeed now that the issue has come
up I want it a lot) is a matter of prioritization. Persistence is necessary
to have a minimally complete language. More powerful immutables could
actually be postponed until version 2 (in a versioning nomenclature where we
have not yet released version 1 yet).

--marcs