Simplified Common Lisp reference
Symbol class: Functions, Evaluation, Flow Control, Definitions and Syntax
Symbol type: special form
fletbindingsbody(zero or more) => an object
Argument description:
bindings list containing function definitions
body program code in which definitions above are effective, implicit progn

FLET is special form for local function binding. Bindings are not recursive and cannot refer to each other. Each binding contains function name, arguments, and function body. See LABELS, DEFUN, LAMBDA.

(flet ((sin2x (x) (sin (* 2 x)))
       (cos2x (x) (cos (* 2 x))))
 (+ (sin2x 0.2) (cos2x 0.2)))
=> 1.3104793
Function indexFull documentation for flet (HyperSpec)