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Held: Monday, March 8, 2010
Summary: We begin our exploration of recursion, the most general form of repetition available in Scheme. You can use recursion to both build and iterate over different kinds of values. Today, we explore how you use recursion to build simple numeric values from lists, and how to remove elements from lists.
(define proc (lambda (val) (if (base-case-test) (base-case val) (combine (partof val) (proc (update val))))))
(define proc (lambda (lst) (if (null? lst) null-case (combine (onestep (car lst)) (proc (cdr lst))))))
(define proc (lambda (lst) (if (null? lst) null-cse (let ((recursive-result (proc (cdr lst)))) (if (test) (combine1 (step1 (car lst)) recursive-result) (combine2 (step2 (car lst)) recursive-result))))))
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