Years ago I read an article or paper about writing a lisp compiler. The compiler started with regular looking lisp, then through macro expansion lisp primitives were defined in terms of each other. Then the small subset of lisp primitives were expanded to goto's and conditionals. The gotos and conditionals were still expressed in lisp S Expressions. Finally the gotos and conditionals were implemented in terms of assembly looking lisp primitives. Then they removed the parentheses and it left an assembly program.

I can't remember the name of the paper. Any ideas? It was such an elegant way of walking through a compiler implementation.