MarkdownPapers is a Java implementation of Markdown language created by John Gruber which provides an easy-to-read, easy-to-write plain text format that takes many cues from existing conventions for marking up plain text in email.
This implementation consist in parser built from a JAVACC grammar definition that produces an abstract syntax tree (AST) where transformations are performed following the Visitor Pattern.
MarkdownPapers is a cross-platform utility capable of running on any operating system that comes with Java support (e.g. Mac OS X, Windows, Linux).
Detailed instructions on how to install and use the MarkdownPapers utility on your Mac are available HERE.