python で関数合成

f.py

from functools import reduce

def f_add(x):
    def __add(y):
        return x + y
    return __add

def f_mul(x):
    def __mul(y):
        return x * y
    return __mul

def do(f):
    def __do(x):
        f(x)
        return x
    return __do

def f(*funcs):
    def __f(initializer):
        return reduce(lambda x, f: f(x), funcs, initializer)
    return __f

proc = f(
        f(
            f_add(2),
            do(print),
            f_mul(2),
            do(print),
            f_add(3),
            do(print),
        ),
        f(
            f_add(3),
            do(print),
            f_mul(2),
            do(print),
        )
    )
print("result: ", proc(4))