maryrosecook/tinylisp — pull request #2 by mtornwall (2013-06-20 19:30:21+00:00)
Title: Let forms

Introduced the (let[rec] ((name expr) ...) body) forms, which evaluate
body in an environment where all the name(s) ... are bound to the result
of evaluating the corresponding expr(s) ..., either in the surrounding
environment (let) or in the body's environment as it's being built (letrec).