Integrating the compiler with unit testing

The document discusses integrating compilers and unit testing by treating the compiler as part of the programming language. It mentions reasons why the Lisp programming language is effective, including compiler macros and directives that allow separating ideas from implementation details. The document also raises the problem that provably correct optimizations are difficult but suggests a solution is trial-and-error testing that can serve as both proofs and benchmarks for compiler correctness and evolution.