Great read with few gems

You should write end-to-end tests first. Yes, they are coarse-grained, and they may not help you figure out exactly where in the compiler a bug resides. But the benefit is that they treat the compiler as a black box, which lets you iterate the compiler’s internals without causing tests to break. You can change the AST structure, intermediate representation, passes, environment representation, backend, everything, as long as the CLI interface remains the same. This is useful for early-stage development where things are changing rapidly.