[vidarh]

> and turning them into a rich AST structure.

This is not a necessary step, and is specifically not done in a lot of simpler compilers. E.g. most "Wirth-type" compilers never build an AST.

There are lots of good reasons to build ASTs if you want to do complex analysis and optimisation, and it simplifies the presentation of some things, but calling the code generator module straight from the parser in many ways makes the direction connection clearer.