resolver.py

class Resolver(object):
    def __init__(self, fn = lambda x:x):
        self._fn = fn

    def __getattr__(self, attr):
        return Resolver(lambda x: getattr(self._fn(x), attr))

    def __getitem__(self, key):
        return Resolver(lambda x: self._fn(x)[key])

    def __call__(self, *args, **kwargs):
        return Resolver(lambda x: self._fn(x)(*args, **kwargs))

    def __add__(self, other):
        return Resolver(lambda x: self._fn(x)+other)

    def __sub__(self, other):
        return Resolver(lambda x: self._fn(x)-other)

R = Resolver()

def apply(res, obj):
    return res._fn(obj)

if __name__ == '__main__':
    class Foo(object):
        def bar(self, x):
            return (x, x+2, x+4)
    
    print(apply((R.bar(3)[2]+7) - 1, Foo()))