Writing code for tests, on paper, has been a thing in CS for quite awhile. While writing lisp for tests, I used to sometimes write the code with no parens (usi

Writing code for tests, on paper, has been a thing in CS for quite awhile. While writing lisp for tests, I used to sometimes write the code with no parens (using indentation to denote nesting). Then I'd go back and add parens where appropriate. defun add-pos-only v1 v2 let sum 0 if and > v1 0 > v2 0 + v1 v2 nil