KoalaRainbow :: ToDo

• Create a mapping function or syntax that performs mapping.
• Goal: Support finding the min and max message post length.
• ex: max(map(len, $msgs/text)) problem: functions are not first order, could be resolved via using &len or something similar.
  
• ex: max(len@$msgs/text) works: new special syntax would implicitly handle the special case.
  
• Implement sorting.
• ex: "sort(/foo, bar)", problem: current constraint propagation bubbles up, does not force down.
  
• ex: "/foo::bar", sort global set foo by bar.  Yet another confusing parallel to XPath syntax, but has the benefits of both being obvious and easily implemented for constraint propagation.  In the case where we're not going on a global set, it can easily call a sorting algorithm.
• Issue of how to indicate numeric sorting versus alphabetic sorting.  Although the database knows the types of the data it is sorting,
  
• Issue of how to indicate ascending versus descending.  Suggest prepending '+' (default if omitted) for ascending, and '-' for descending.
  
• Text-mode support
• Build abstract action tree once rather then using MT builder repeatedly.
• More string functions:
• some kind of regex match, count match, search/replace.