#+BEGIN_SRC scheme :session ch1 :exports both
  (define (check-it x)
   (cond
    ((string? x) (string-length x))
    ((number? x) (if (<= x 0) x (- x 1)))
    ((boolean? x) (if (and #t x) 10 20))
    (else #f)))

#+END_SRC

#+RESULTS:


#+BEGIN_SRC scheme :session ch1
(define (square x)
 (* x x))

#+END_SRC

#+RESULTS:

#+BEGIN_SRC scheme :session ch1
(check-it "Foobar")
#+END_SRC

#+RESULTS:
: 6

#+BEGIN_SRC scheme :session ch1
(square 5)
#+END_SRC

#+RESULTS:
: 25

#+BEGIN_SRC scheme :session ch1 :exports both
(define (bool-imply a b)
 (if (or (not a) b) #t #f))
#+END_SRC

#+RESULTS:

#+BEGIN_SRC scheme :session ch1 :exports both
(bool-imply #t #f)
#+END_SRC

#+RESULTS:
: #f

#+BEGIN_SRC scheme :session ch1 :exports both
map
#+END_SRC

#+RESULTS:
: #<procedure map (f l) | (f l1 l2) | (f l1 . rest)>