From: Mathieu Bouchard <matju@...>
Date: 2001-10-28T23:00:21+09:00
Subject: [ruby-talk:23682] Re: [ANN] RubyInRubyParser 0.1-pre-alpha


On Fri, 26 Oct 2001, Robert Feldt wrote:
> On Fri, 26 Oct 2001, Mathieu Bouchard wrote:
> Some q's though:
> * Is Tuple the place to add methods I want all "nodes" in the AST to have?

Well, Tuple is outside of the AST system, so adding to it will also add to
every other program using Tuple; for example, most classes in RubyX11
inherit from Tuple. (except that RubyX11 still has its own copy of
Type.rb with X11:: prefixes...)

> * Maybe have all schemas derive from RubySchema and then have
>     class RubySchema < Tuple; end
>   since Tuple is too general in this context? Or include empty RubySchema
>   module? Anyway, we should have a way to add to all RubySchemas/Ast nodes
>   without having to add to tuple.

A "Schema" module is a set of class definitions, type definitions, module
inclusions, etc. such that as a whole it describes a syntaxless language.

A "Schema" gets not instantiated.

Every Schema would have its type constraint on toplevel nodes. I don't
know how I'd specify that in code. For now, in RubySchema, Body would be a
good toplevel node, but I'm not sure it's the only such node that can
reasonably be produced by a parser.

> * IMHO, maybe we should avoid too short names (like M) and call the
> RubySchemas by their "full" name (M => Message, IVar => InstanceVariable
> etc) and then have the shorthands be aliases (M = Message etc)? Makes
> things self-descriptive even if your new to them and if this will be a
> "standard" way of representing parsed Ruby programs it might affect not
> only the "internals hackers"...

I'll think about this one. However, M is not a message in the strict
sense; it's a message expression; so to evaluate it you have to first
evaluate its subcomponents and construct a real message from it, and then
evaluate that message.

> * Is schema commonly used in this context? Is it from Lisp? I'm more used
> to "Term"...

Tuple (now called Form, if you're getting metaruby from the cvs) is
possibly like the Term you're talking about.

"Schema" is terminology I borrowed from XML to say "a specialized language
defined in terms of data structures instead of sequences of characters".

No special relationship to the Scheme language. (But I intend to use a
Lisp-like syntax as a notation for data structures eventually)

________________________________________________________________
Mathieu Bouchard                   http://hostname.2y.net/~matju