This chapter will walk through the creation of a simple variant of Awk (only
loosely following the POSIX specification). It will probably have several
sections. It will provide an example of a full project based on
pest with a
manageable grammar, a straightforward AST, and a fairly simple interpreter.
This Awk clone will support regex patterns, string and numeric variables, most of the POSIX operators, and some functions. It will not support user-defined functions in the interest of avoiding variable scoping.