YAML config file parser

[Paul Prescod]

A.M. Kuchling wrote:
>...
> 
> Non-programmers don't edit configuration files, though; they use a GUI that
> presents a nice interface, and never see whatever format the settings are
> stored in. 

It is precisely to enable the construction of these interfaces (and 
other introspective tools) that it is better that these configuration 
files not be Turing complete. What does the interface do when the 
setting of a particular property depends on some complicated code? What 
does it show the user about what the property means. Compare the 
difficulty of building an app that reads and displays INI files to one 
that introspects Python code!

  Paul Prescod