Squareroot in Lisp en Red

gistfile1.txt

; https://repl.it/languages/scheme

(define (abs x)
  (cond ((> x 0) x)
        ((= x 0) 0)
        ((< x 0) (- x))))

(define (average x y)
  (/ (+ x y) 2))

(define (square x) (* x x))

(define (improve guess x)
  (average guess (/ x guess)))

(define (good-enough? guess x)
  (< (abs (- (square guess) x)) 0.001))

(define (new-if predicate then-clause else-clause)
  (cond (predicate then-clause)
        (else else-clause)))

(define (sqrt-iter guess x)
  (if (good-enough? guess x)
          guess
          (sqrt-iter (improve guess x)
                     x)))

(define (sqrt x)
  (sqrt-iter 1.0 x))

(sqrt 3)

; met new-if eindeloze lus.

; nu in Red
abs: function [
    x
][
    case [
        (x > 0) [return x]
        (x = 0) [return 0]
        (x < 0) [return negate x]
    ]
]

average: function [
    x y 
][
    (x + y) / 2
]

square: function [
    x
][
    x * x
]

improve: function [
    guess x
][
    average guess (x / guess)
]

good-enough?: function [
    guess x
][
  (abs ((square guess) - x)) < 0.001
]

sqrt-iter: function [
    guess x
][
	print guess
    either good-enough? guess x [
        guess
    ][
        sqrt-iter (improve guess x) x
    ]
]

sqrt2: function [
    x
][
    sqrt-iter 1.0 x
]