ch1-1-7-square-roots-with-new-if.scm

; A block-structured and lexically scoped version of finding square roots.
; With Alyssa P. Hacker's new-if 
(define (average x y)
	(/ (+ x y) 2))

(define (new-if predicate then-clause else-clause)
	(cond (predicate then-clause))
	(else else-clause))
	
(define (sqrt x)
	(define (good-enough? guess)
		(< (abs (- (square guess) x)) 0.0001))
	(define (improve guess)
		(average guess (/ x guess)))
	(define (sqrt-iter guess)
		(new-if (good-enough? guess)
			guess
			(sqrt-iter (improve guess))))
	(sqrt-iter 1.0))