Io Syntax Parser

This bit of code is a lexer and parser combination for the syntax defined by the Io programming language. Note that this parser, while it can be used to parse Io sources, lacks several features needed to retain Io's semantics:

Comments. This should be added to the lexer.
Syntactic Sugar. This should be added as a layer on top of the parser in this module.
Error reporting. Utterly non-existant.

Now you see why this content is in the "ideas" section of my web site. Nonetheless, despite its limitations, it's proven to be pretty educational. Indeed, it's whole purpose was to educate myself on the requirements needed to parse Io's syntax. It turns out to not be that much. Indeed, it's only marginally more sophisticated than Lisp's syntax. Supporting Io's desugaring layer would definitely add to the system's complexity, however.

Sugar Layer

There are two features provided by the sugaring layer of Io:

First, it provides normal, C-like arithmetic operator precedence. This allows you to type expressions like 32 + 180 * degreesC / 100 and have it "just work." Without this, you'd have to write the code like degreesC /(100) *(180) +(32), since arithmetic operators are just messages, like everything else in the language.
Second, the sugar layer provides a convenient assignment and update syntax, which allows you to type in convertCtoF := method(degreesC, 32 + 180 * degreesC / 100) instead of setSlot("convertCtoF", method(degreesC, 32 + 180 * degreesC / 100)).

I'm not aware of any additional sugaring requirements.

Downloading io_parser.py

The software is written in Python, so it ought to "just work" provided you have Python 2.5. It may also run on 2.4 as well, but don't hold me to it.