>>>>> "DC" == Damian Conway <dam...@conway.org> writes:
DC> * Grammars built into the language:
DC> grammar Expr::Arithetic {
DC> rule Expression { <Mult> ** $<OP>=< + - > }
DC> rule Mult { <Pow> ** $<OP>=< * / % > }
DC> rule Pow { <Term> ** $<OP>=< ^ > }
DC> token Term {
DC> <Literal>
DC> | '(' <Expression> ')'
DC> }
DC> token Literal { <[+\-]>? \d+ [ \. \d+ ]? }
DC> }
DC> * Grammar inheritance:
DC> grammar Expr::Algebraic is Expr::Arithetic {
DC> token Literal {
DC> <alpha>+
DC> | <Expr::Arithetic::Literal>
DC> }
DC> }
when i promote p6, the first and biggest thing i talk about
grammars. many of the other neat things (and damian listed a good bunch)
can be found in other langs or are nice but focused and small. p6
grammars are like nothing out there especially in any mainstream lang
today. and they are BIG in scope of what they can do. also they are very
accessible to newbies as they are based on the familiar regexes we all
use (and in almost all modern langs too). the mapping of grammar rules
to methods/subs and inheritance (which i generally despise but is
totally appropriate in grammars) is also amazing. now you can use
grammar libs and customize them as desired with little effort. before
this if you did have a grammar/parser (in any lang/system) you had to
learn its guts in detail before you dared to touch it. also grammars can
do dynamic things like build up a parsed data tree on the fly. you will
get what you expect (DWIM) with arrays of repeated grabbed sections
(properly nested as it follows your grammar). these are holy grails of
parsing and they come built in with incredible ease of use. note how
every other lang claims a perl5 compatible regex engine (and they lie as
none can do s///e among other things :). now with p6 they will never be
able to copy its grammars as it is a core part of p6 and not some regex
lib.
so you can talk about this amazing feature and be assured that the
audience will be amazed. :)
thanx,
uri
--
Uri Guttman ------ u...@stemsystems.com -------- http://www.sysarch.com --
----- Perl Code Review , Architecture, Development, Training, Support ------
--------- Free Perl Training --- http://perlhunter.com/college.html ---------
--------- Gourmet Hot Cocoa Mix ---- http://bestfriendscocoa.com ---------
