Alan Manuel Gloria:
> There's a subtle problem with ". $" though...
>
> First:
>
> a $ b
> ===>
> (a b) ; as described in the rationale for SUBLIST.
>
> Then:
>
> a . $ b
> ===>
> (a . b)
>
> ???

Bug, and I think fixed.  Current development version of
"unsweeten" and the ANTLR implementation seem to work.
The Scheme implementation now does this:

$ printf 'a . $ b\n\n' | ./unsweeten
(a b)

Supporting ". $" does have a slight annoyance; it creates a minor
ambiguity in the grammar (basically, like a "dangling else" clause in many langauges).
I've been able to avoid those so far.  It's not a crisis, because we can
easily make it go first, but it is an annoyance.

--- David A. Wheeler