[R6RS] string escapes

[William D Clinger]

Matthew wrote:
> My hesitation is that some Scheme systems already support C-like
> escapes, and they may accept the former and treat it as "a;p;p;l;e;"
> instead of "apple". It's a minor hassle, but for this reason I still
> slightly prefer \x<X...>.

If we're serious about replacing the "is an error"
language of R5RS with "must raise a &lexical exception",
then either syntax would require all implementations to
raise an exception if they see "\x61\x70\x70\x6c\x65".

Matthew's concern is not an issue unless we aren't really
serious about requiring implementations to raise exceptions
for lexical errors.

I assume we're serious, so I too prefer \xXXX...; for
specifying random Unicode characters in strings.

Will