Kudos. I'm actually really liking ANTLR! I have a pretty darn good velocity with a rapid prototyping project I am doing in my Google 20% time. For example, I just discovered a feature in rewrite rules that does exactly what I need (referencing previous rule ASTs, p. 174 in your book). It took me about 5 minutes to get this to work and remove an ugly wart from my grammar. Hats off! Guido van Rossum, Inventor of Python

Samuel Luckenbill, Senior Manager of Search Infrastructure, Twitter, inc. ANTLR is an exceptionally powerful and flexible tool for parsing formal languages. At Twitter, we use it exclusively for query parsing in Twitter search. Our grammars are clean and concise, and the generated code is efficient and stable. The book is our go-to reference for ANTLR v4 -- engaging writing, clear descriptions and practical examples all in one place.

Just wanted to take the opportunity to say thanks. ANTLR is a BIG improvement over yacc/lex, and your support for it most commendable. Managed to get my tired old brain around it in a day. Nice work! Brad Cox, Inventor of Objective-C