integer arithmetics

[John W. Eaton]

On  2-Oct-2008, Jaroslav Hajek wrote:

| I'm not sure. I can easily imagine people complaining that 2*a for a
| of int64 type isn't working. But I can maybe play with it a while
| longer.

Can we detect and warn about loss of precision?  Or make that an
error?  In that case, I guess the range of values handled would be
smaller, but at least we could handle the most common cases and also
not produce incorrect results.  But maybe that is worse than not
having the feature?

jwe