Expand docs on Parser

[skybrian]

Most of the operators and methods on Parser have cryptic comments. For example:

/// Applicative <*>
Parser operator *(Parser p) => this >> (f) => p >> (x) {
Function ff = f;
return success(ff(x));
};

I think most Dart developers will be entirely mystified by this comment. It would be more user-friendly explain what this operator does without assuming you know Haskell or have read the research papers.

[polux]

Sure, this comment was mainly here for myself, It's almost a private method. I know the doc sucks currently, it's my plan to do something about it someday :)

[atebitftw]

The guide you have here is a great start http://polux.github.io/parsers/. Would you completing the section on recursion when you get a chance? :)

[polux]

@prujohn see issue #13 .