forward.py

from functools import wraps

import leloop


def mount(scene, init, view):

    state = init()

    def spawn(timeout, callback, *args, **kwargs):
        # spawn is easier to test that leloop.call_later
        leloop.call_later(lambda : yield from callback(*args, **kwargs), timeout)

    def make_reducer(func):  # called make action in forward project
        """This calls `func` with the current `state` as argument and `spawn`"""
        @wraps(func)
        def wrapped(*args, **kwargs):
            new = func(state, spawn, *args, **kwargs)
            if new != state:
                state = new
                render()

        return wrapped

    def render():
        new = view(state)
        new.update_callback(make_reducer)
        scene.patch(new)
        return new

    def change(func, *args, **kwargs):
        func(state, spawn, *args, **kwargs)
        
        
    return make_reducer