Thanks for writing this. I find your writing style to be very easy to follow. I've wanted to play with a toy language for some time, so I'm very excited to dive into your book with both feet. I'm working on Windows and am up to chapter 6. Very enjoyable. The only suggestions I would offer is perhaps to mention that AST stands for Abstract Syntax Tree. It seems this book is targeted to less experienced programmers, so it may be helpful to mention what AST means in this context. Thank you for your hard work and willingness to share your knowledge.