2 days ago
my attempt to do the exercises in sicp.
Wednesday, July 16, 2008
sicp exercise 2.23
; Exercise 2.23. The procedure for-each is similar to map. It takes as arguments a procedure and
; a list of elements. However, rather than forming a list of the results, for-each just applies
; the procedure to each of the elements in turn, from left to right. The values returned by
; applying the procedure to the elements are not used at all -- for-each is used with procedures
; that perform an action, such as printing. For example,
; (for-each (lambda (x) (newline) (display x)) (list 57 321 88))
; The value returned by the call to for-each (not illustrated above) can be something arbitrary,
; such as true. Give an implementation of for-each.
(define for-each (lambda (proc items)
(cond ((null? items) 1)
(else (proc (car items)) (for-each proc (cdr items))))))
(for-each (lambda(x) (display x)(newline)) (list 1 2 3 4 5))