Compiler written in C++ to compile COOL (Classroom Object Oriented Language)
Based on this lovely MOOC: Compilers at Stanford, maybe from 2000's
Decided to desist and deprecate. I did a watered down compilers course with creating a lookup table/tokenizer/parser/maybe AST. I had no curiosity or much ability for professional level work in this domain. I believe there is no real reason to cross the boundary from software engineer to computer scientist without honest love for computer science and going full metal in what it takes.