Looks like this book is out now. Book contents:

• How to build an interpreter for a C-like programming language from scratch

• What a lexer, a parser and an Abstract Syntax Tree (AST) are and how to build your own

• What closures are and how and why they work

• What the Pratt parsing technique and a recursive descent parser is

• What others talk about when they talk about built-in data structures

• What REPL stands for and how to build one