Re: More PEG

[Ludovic Courtès]

Hi Noah,

Noah Lavine <address@hidden> skribis:

> It looks to me like the last thing needed before the peg branch can be
> used is to change some of the S-expression representations of the
> components. Here are the five that I think need changing, taken from
> the manual, with suggested replacements.

This looks like interesting stuff!

The syntactic changes you propose all make sense to me, FWIW.

[...]

> There's something I'm still a little unsure about, though. It's
> possible to get deeply nested S-expressions, like '(+ (and (* "a")
> "b")). Since +, * and ? only ever take one argument, it is possible to
> shorten such a list by letting people merge those elements into the
> next item, like this: '(+ and (* "a") "b").

I would rather keep it simple and avoid shortcuts that may end up being
confusing.

A more general question about PEG: how do you bind a variable to the
result of a pattern?  For instance, if you want the result of (* "a") to
be bound to variable X–just like (match '(1 2 3) ((a _ ...) a)) binds A
to 1.

Thanks,
Ludo’.