Re: Combining mutable objects with const references

Ah, Clean... interesting. "Uniqueness type." I will have to read more
before I can really comment. Thanks for the link.

Joachim, I am suggesting that it would be a good idea for the compiler
to not allow keeping the old value. It doesn't have to enforce this,
but if it does then we can be sure that a value only refers to what it
was originally referred to. For instance:

let p = new point(1, 1) in
let q = p except .x = 3

Now q is equivalent to "new point(3, 1)", except that it has used the
underlying storage that p used. In most cases, the program has no need
for p anyway, after it has been used to produce q.

There are times when this would restrict the programmer (for example,
if a circularly-linked list was desired), but this special usage
should be made distinct. Or at least, that's what I'm suggesting.

Pat