ex1.5.py

def p():
    return p()

def test(x, y):
    return 0 if x == 0 else y

test(0, p())

sicp-a-b.py

from operator import add, sub

def a_plus_abs_b(a, b):
    return (add if b > 0 else sub)(a, b)

sicp-a-b.scm

(define (a-plus-abs-b a b)
  ((if (> b 0) + -) a b))

sicp-aplicative.py

# applicative order normal order
f(5) f(5)
sum_of_squares(5+1, 5*2) sum_of_squares(5+1, 5*2)
sum_of_squares(6, 10) square(5+1) + square(5*2)
square(6) + square(10) ((5+1) * (5+1)) + ((5*2) * (5*2))
(6 * 6) + (10 * 10) (6 * 6) + (10 * 10)
36 + 100 36 + 100
136 136

sicp-average.py

def average(x, y):
    return (x + y)/2

sicp-blocks.py

def sqrt(x):
    def is_good_enough(guess, x):
        return abs(square(guess) - x) < 0.001

    def improve(guess, x):
        return average(guess, x/guess)

    def sqrt_iter(guess, x):
        if is_good_enough(guess, x):
            return guess
        else:
            return sqrt_iter(improve(guess, x), x)

    return sqrt_iter(1.0, x)

sicp-dis.py

>>> import dis
>>> dis.dis(square)
1 0 LOAD_FAST 0 (x)
3 LOAD_FAST 0 (x)
6 BINARY_MULTIPLY
7 RETURN_VALUE

>>> dis.dis(square2)
1 0 LOAD_FAST 0 (x)
3 LOAD_FAST 0 (x)
6 BINARY_MULTIPLY
7 RETURN_VALUE

sicp-good-enough.py

def is_good_enough(guess, x):
    return abs(square(guess) - x) < 0.001

sicp-improve.py

def improve(guess, x):
    return average(guess, x/guess)

sicp-lambda-var.py

square2 = lambda x: x * x

sicp-lambda.py

lambda x: x * x

sicp-lex-scope.py

def sqrt(x):
    def is_good_enough(guess):
        return abs(square(guess) - x) < 0.001

    def improve(guess):
        return average(guess, x/guess)

    def sqrt_iter(guess):
        if is_good_enough(guess):
            return guess
        else:
            return sqrt_iter(improve(guess))

    return sqrt_iter(1.0)

sicp-myabs.py

def myabs(x):
    if x > 0:
        return x
    elif x == 0:
        return x
    elif x < 0:
        return x

sicp-myabs2.py

def myabs(x):
    if x < 0:
        return -x
    else:
        return x

sicp-myabs3.py

def myabs(x):
    return -x if x < 0 else x

sicp-sqrt.py

def sqrt(x):
    return sqrt_iter(1.0, x)

sicp-sqrt_iter.py

def sqrt_iter(guess, x):
    if is_good_enough(guess, x):
        return guess
    else:
        return sqrt_iter(improve(guess, x), x)

sicp-square-use.py

square(2 + 5)
square(square(7 + square (3)))

sicp-square.py

def square(x):
    return x * x

sicp-sum-squares.py

def sum_of_squares(x, y):
    return square(x) + square(y)

sum_of_squares(3, 4)

def f(a):
    return sum_of_squares(a + 1, a * 2)