| 1234567891011121314151617181920 |
- (define (insert-word word histogram)
- (let loop ((h histogram))
- (if (null? h)
- (cons (cons word 1) histogram)
- (let ((entry (car h)))
- (if (equal? word (car entry))
- (begin (set-cdr! entry (+ 1 (cdr entry)))
- histogram)
- (loop (cdr h)))))))
- (define (count-words p)
- (let loop ((word '()))
- (let ((char (read-char p)))
- (cond ((eof-object? char) '())
- ((whitespace? char)
- (if (null? word)
- (loop '())
- (insert-word (list->string (reverse word)) (loop '()))))
- (else (loop (cons char word)))))))
|
