The application is a demonstration on how to build a parse tree for math expressions like following:
A + B * (C + D) + E
The grammar is the following:
E -> TR
R -> +TR | e
T -> (E) | var
The application implements the concept of 'monadic parser combinator' described here: http://www.cs.nott.ac.uk/~pszgmh/monparsing.pdf