A math course built a compiler that compiles itself
not-abc is a teaching compiler written entirely in itself: just 64-bit values, no static type checking, and a handful of built-ins, yet the whole toolchain is complete. It comes out of Michael Lehn's undergraduate HPC course, a live demo that a surprisingly small language can host a full compiler. Reading how the bootstrap works is a fast way to un-mystify compilers for anyone who skipped the CS courses.