An example might make the
concept more clear. The
canonical example of mutually recursive functions is
even? and
odd?. Here they are, in
Scheme:
(define even?
(lambda (n)
(if (zero? n)
#t
(odd? (- n 1)))))
(define odd?
(lambda (n)
(if (zero? n)
#f
(even? (- n 1)))))