Comment by pshirshov

My personal experience of writing various DSL/general purpose compilers (I've created at least 4 DSL compilers and one general purpose) is kinda different from the books I've read.

Scala is an awesome language which frees one from working on many boring details and makes it possible to keep the codebase tiny. With such an expressive language I can concentrate on the logic instead of thinking about minor things.

We have enough memory and cpu power to use worse than linear algorithms without noticeable performance impact.

Parsers aren't an issue at all in our days, peg combinators like fastparse allow one to be extremely productive.

I tend to stick to immutable multi-staged pipelile with several immutable trees, use error-accumulating data structures (Either[NonEmptyList[Issue], T]), explicitly express entity (eg type definition) dependencies as graphs (which can be processed iteratively and in parallel).