From jacobson@math-cs.cns.uni.edu Mon Feb  9 08:11:38 2004
Date: Fri, 06 Feb 2004 09:55:29 -0600 (CST)
From: Mark Jacobson <jacobson@math-cs.cns.uni.edu>
To: 810-151-04@uni.edu
Subject: [810-151-04] Scheme discussion followup...


Welcome to DrScheme, version 204.
Language: Textual (MzScheme, includes R5RS).

> (map power '(2 4 6 8))
map: arity mismatch for procedure power: expects 2 arguments, given 1

> (map power2 '((2 4) (2 6) (2 8)))
(16 64 256)

> (apply + (map power2 '((2 4) (2 6) (2 8))))
336

(define (power n m)
  (expt n m))

(define (power2 li)                 <------ accepts a LIST of
  (expt (car li) (cadr li)))                the two arguments.

> (apply + (map power2 '((2 4) (2 6) (2 8)))) <--- List of lists
336                                                is okay to map
                                                   power2 procedure
                                                   to.
   I will post your next assignment to the
   web page shortly, probably before 11 a.m.

   Mark

(define t1 '())
(define t2 (insert 44 t1))
(define t3 (insert 22 t2))
(define t4 (insert 33 t3))
(define t (insert 11 t4))
(define t (insert 9 t))
(define t (insert 16 t))
(define t (insert 55 t))

Welcome to DrScheme, version 205.
Language: Textual (MzScheme, includes R5RS).
> t1
()
> t2
(44 () ())
> t3
(44 (22 () ()) ())
> t4
(44 (22 () (33 () ())) ())
> t
(44 (22 (11 (9 () ()) (16 () ())) (33 () ())) (55 () ()))