I bet you could go quite far writing a straightforward compiler using an S-expr syntax.

Any by a "compiler" I'm talking doing something simply like taking Pascal, converting it to an s-expr grammar, and going to town.

Scheme can be a simple algol style language. Using s-expr syntax just made your lexer/parser much simpler. And (simple) compilation is really not that hard (just compile it to C for your first crack if you want).

I bet you could get quite far quite quickly.