doesn't that make you wonder?

[John MacFarlane]

+++ Tao Klerks [Oct 20 11 12:52 ]:

>    OK, I interpret this (besides the quite-reasonable "why should I care?"

>    vibe), combined with previous references to the PEG grammar(s) implicit

>    in MultiMarkdown and peg-markdown's implementations, as "a formal

>    specification already exists".

> 

> 

>    That sounds fine - I'd love to use peg-(multi)markdown in my programs,

>    but I see two practical problems for that right now:

> 

>    ·         A C library, while portable to any processor architecture, if

>    not portable to any development environment, and certainly not

>    future-proof. I, personally, would like to be able to rely on the exact

>    same syntax not only across the OSs that Fletcher mentions, but also in

>    C# code (that can be sandboxed safely - no P/Invoke calls to unsafe

>    code) and also in browsers. There are numerous other environments

>    (Java, etc) where a similar "safe code" requirement precludes the use

>    of a C library (at least in browser and other high-sandboxing

>    environments).

> 

>    ·         The PEG grammars(s) may be formal reproducible reusable

>    specifications, but my understanding is that they are not so meaningful

>    without a definition of what they map to. If my brief reading on this

>    is correct, a PEG grammar allows you to define behaviours to be

>    executed upon encountering certain source structures; those behaviours

>    implement a conversion to HTML, or latex, or whatever, but are implicit

>    in the Program, not the Specification/Grammar

> 

> 

>    So if we take the current PEG-based implementations as a starting

>    point, what would it take to produce a specification that formally

>    establishes not only the source structures to be matched, but also the

>    behaviour/conversions to be implemented against them? Is this just a

>    question of detailed documentation and an open test-suite?

> 

> 

>    Another applicable question is: are PEG grammars easily usable in other

>    environments? A brief search suggests so (js:

>    [1]http://stackoverflow.com/questions/79584/are-there-any-parsing-expre

>    ssion-grammar-peg-libraries-for-javascript-or-php, C#:

>    [2]http://www.codeproject.com/KB/recipes/grammar_support_1.aspx not

>    GPL-compatible, sadly…); does anyone know how fesible it is to take the

>    existing PEG grammar(s) and reuse them in other languages?


Translation of peg-markdown to Go:  https://github.com/knieriem/markdown

Java markdown parser based on peg-markdown: https://github.com/sirthias/pegdown

And of course a PEG could provide a reference specification even for
implementations that use other parsing methods.

John