Re: [Akim Demaille] Naming the symbols

[Akim Demaille]

>>> "Paul" == Paul Eggert <address@hidden> writes:

 > Akim Demaille <address@hidden> writes:
 >> - use this syntax, it is human readable and natural.

 > I dunno, I find it a bit hard to read, with ":" being overloaded so
 > seriously, not only in the grammar, but also in your C++ code.  There
 > sure are a lot of colons there.

Yep.  But of course there is code between braces that also help
keeping the rhythm.

 > As long as you're redoing the syntax, why not go all the way and use
 > "->" rather than ":" to separate the head of the grammar from the
 > body?  Then, you can allow your extension only for new-style grammar
 > rules that use "->".  Something like this:

 >    r:exp ->
 >      "if" c:exp "then" t:exp
 >       { r = new ast::IfExp (c, t); }
 >> "if" c:exp "then" t:exp "else" e:exp
 >       { r = new ast::IfExp (c, t, e); }
 >    ;

 > You can insist on a terminating ";" here, of course.

I resisted this idea because I don't like when TMTOWTDI.  But why not
indeed.

But then, why -> instead of the more traditional `::='.  Both are OK.

 > I'd think this extension would be LALR(1), if you play your cards right.

That's not clear to me, if you consider things like

       exp: exp '+' exp
       exp -> exp '-' exp

we have the same problem: where does the first rule end.  I still
think dropping the scanner hacks and moving towards using the GLR
parser is a better road.  Whatever the syntax we choose.  And then,
there is no longer any need to define two syntax for rules, we merely
define several syntax for the `->' token.