Question

When I started writing this question, I didn’t think of the easy solution with nested lists, but now anyway want to find one.

Here’s an ugly code:

fun0(
    fun1(fun2(fun3(arg1))),
    fun1(fun2(fun3(arg4))),
    fun1(fun2(fun3(arg4))),
    fun1(fun2(fun3(arg4))))

Ouch! Names are given for examples. In the real application, their names have no pattern like this.

I played a bit with map(map ...) and reduce(map ...) getting wrong results or TypeErrors, before going here and writing this. The simple solution, of course, came while writing the question: use list comprehensions. Something like this (haven’t tested yet):

fun0([i(j) for i in (fun1, fun2, fun3) for j in (arg1, arg2, arg3, arg4)])

Still, I’d like to know how is it possible to achieve the same with functional programming tools only?

fun0(map(fun1, map(fun2, map(fun3,
(arg1, arg2, arg3, arg4)))))

There’s still a pattern that I think can be removed. I tried map(map, (fun1, ...), (arg1, ...)) but this way Python tried to iterate over each argument and raised errors.

Answer 1

your 3 examples do 3 different things.

your original is the same as

fun0(map(lambda x:fun1(fun2(fun3(x))), [arg1,arg2,arg3,arg4])

your second example, if you absolutely want a functional form, is probably something like

fun0(map(apply, itertools.product([fun1,fun2,fun3],[arg1,arg2,arg3,arg4])))