Complicated AST manipulation looks ugly in C++. How to refactor it?

[Angrboda]

Isn't that the whole point of a compiler, to translate computer code into machine code?  I would ditch the C++ and just use C, modeling your new language on an existing one.  C#, after all, "borrowed" heavily from Java.

Anyone writing complex code in C is crazy or a masochist.  C++ at least has the standard template library (even if it is a pain to learn).

Using C++ allows Flat to potentially compile his compiler into any platform, including webassembly.  Yes, that can be done with other languages, but it isn't easy with garbage-collected languages.

It's a matter of trade-offs. Hand-optimizing C is a lot more effective than trying to optimize object-based code. Time is money with compliers.