| bindings | list of variable - initial value pairs |
| body | program code in which definitions above are effective, implicit progn |
LET is special form for variable binding. Bindings are described in two element lists where the first element specifies name and the second is code to compute its value, or single variable without default initialization. There are also declarations possible before body.
(let (a b (c 3) (d (+ 1 2))) (list a b c d)) => (NIL NIL 3 3)