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Exercise solution:
A straightforward filter function

Here follows a straightforward implementation of filter:

 
(define (filter pred lst)
  (cond ((null? lst) '())
        ((pred (car lst)) 
           (cons (car lst) (filter pred (cdr lst))))
        (else (filter pred (cdr lst)))))

Exercise solution: A straightforward filter function

Exercise solution:
A straightforward filter function