(define variable expression)
(define (variable formals) body)
(define (variable . formal) body)
See R^4RS.
Returns a symbol, the identifier that has been bound.
Definitions may appear anywhere within a local body (e.g. a lambda
body or a let).
If the expression is omitted, void (the non-printing
object) is used.
Examples:
(define nil #f)
(define ((f x) y) (cons x y)) (define (g x) ((f x) 5)) (g 'a) ==> (a . 5)