steppers

stepper.py

from random import random


def busy_block(stepper):
    res = None
    while stepper is not None:
        stepper, res = stepper()
        print(res)
    return res


def bind(stepper, dependent_stepper_maker):
    def wrapper():
        next_stepper, res = stepper()
        if next_stepper is None:
            return (dependent_stepper_maker(res), res)
        else:
            return (bind(next_stepper, dependent_stepper_maker), res)
    return wrapper


def count_steps(stepper, n=1):
    def wrapper():
        (next_stepper, res) = stepper()
        if next_stepper is None:
            return (None, (res, n))
        else:
            return (count_steps(next_stepper, n + 1), (res, n))
    return wrapper


def rand_step():
    v = random()
    if v < 0.9:
        return (rand_step, v)
    else:
        return (None, v)


def build_next_stepper(res):
    v, n = res
    if n != 1:
        return bind(count_steps(rand_step), build_next_stepper)
    else:
        return None


busy_block(bind(count_steps(rand_step), build_next_stepper))