functor.py

class List:
    def __init__(self, items):
        super().__init__()
        self._items = items

    def __call__(self, function):
        self._items = map(function, self)
        return self

    def __iter__(self):
        return iter(self._items)

    @property
    def result(self):
        self._items = tuple(self._items)
        return self._items


def main(data, functions):
    functor = List(data)

    for func in functions:
        functor = functor(func)
        yield functor.result


if __name__ == '__main__':
    stages = main(
        data=(-2, -1, 0, 1, 2, 21),
        functions=(abs, float, str, reversed, list, ''.join, float)
    )

    for stage in stages:
        print(stage)