variable xref

[Mike Kerner]

I don't want to pretend to be an expert on the topic of writing compilers,
since I only ever wrote two, both under the watchful obsession of a
professor, and my lex and parse code were not optimal in either case.  In
general, they were some of the easiest pieces of large code I ever wrote
because the grammars were so rigid and rule-based.  Building forgiveness
into them would have made the poor developer's life easier, even thought
that meant adding a third pass to try to ascertain context instead of
blindly aborting when something didn't exactly fit the formula.

I agree that unquoted literals are not ideal.  I think they should be
deprecated, and I think they should have been removed in 1986, so add that
to the LC10 list.  They have always made reading scripts more difficult.
Readability and approachability are two things that have set xtalk apart.
Unquoted literals detract from that.