John Cowan (regarding Icon):
> If you're worried about it, make sure all continued lines end in _,
> that's all.

This brings up a different point - sweet-expressions do *not*
have a line-continuation capability, as it is currently defined.

One *could* be easily added. One approach would be to interpret "\\" at the
of a line as a line continuation; I even have a draft BNF construction that does
that.  We also dabbled with "." at the beginning
of a line as meaning "this continues the previous line".

But we've tried to *minimize* the number of mechanisms in the notation,
and there didn't seem to be a strong use case.
If the sub-components have structure you can just use
indentation as intended, and if it's just a long list of items, (...) works just fine.
IIRC, John Cowan was concerned that "\\" at the end of a line would be
confusing, too.

For the moment, I'll just document this as a design decision.  If someone wants
to argue for a continuation symbol, please post.

--- David A. Wheeler