I see your point. Option b does suggest that you can read ahead in a
"blocked" list and get undef's. If I had to choose just one, I think
I'd opt for d, but having two zip's one acting like c and one like d
might be useful. Then, of course, my first thought was wrong. This one
may well be, too.
--
That (b) certainly seems like the sensible option to me. My second
choice would be d.
A nice thing about c is that it leaves open the possibility of lazy
evaluation (zip as much of the lists as you can, leaving open the
possibility of picking up the process later). But I still prefer b.
Maybe ther
Come to think of it...I had in mind a sequence of "skip" statements,
that would back out of a level one at a time, until you finally reached
the desired level. But, I think maybe these "skip" statements
essentially play the role of what you called "positive unindent tokens"
(I like that term).
I a
but you still need a stack for global correctness.
--- Larry Wall <[EMAIL PROTECTED]> wrote:
> On Thu, Sep 08, 2005 at 02:16:33PM -0700, Greg Woodhouse wrote:
> : In the case of the
> : "indentation grammar", then the (one) stack in a push-down
> automaton is
> :
That's something I've been thinking about, too. There are a lot of
"interesting" languages that cannot be described by context free
grammars (such as {empty, 012, 001122, 000111222, ...} but very simple
enhancements do make them easy to recognize. In the case of the
"indentation grammar", then the
