University
of Washington • CSE583 • D. Notkin © 2000
37
Tail recursion examples
l(define
(last x)
(if (null? (cdr x)) (car x)
(last (cdr x))))
(if (null? (cdr x)) (car x)
(last (cdr x))))
l(define
(member e x)
(cond ((null? x) #f)
((eqv? e (car x) #t)
(else (member e (cdr x)))))
(cond ((null? x) #f)
((eqv? e (car x) #t)
(else (member e (cdr x)))))
lThe bold-italics
invocations represent the final thing
that the function does
–After that, it’s just a bunch of returns that don’t “do” anything