I actually don't care that much about the monadic functions.

For me the important use case is pattern matching, which C++ doesn't yet have. Pattern matching really changes how you see the entire language.

C++ has pattern matching through overloading.

How do you figure?

I don't understand the question.

Here is the first example I found on Google if that helps you understand.

    std::variant<Fluid, LightItem, HeavyItem, FragileItem> package;

    std::visit(overload{
        [](Fluid& )       { std::cout << "fluid\n"; },
        [](LightItem& )   { std::cout << "light item\n"; },
        [](HeavyItem& )   { std::cout << "heavy item\n"; },
        [](FragileItem& ) { std::cout << "fragile\n"; }
    }, package);

But that's not really even a pattern match? Here's what a pattern match looks like: [This is from day 10 of last year's Advent of Code.]

            match (state, pipe) {
                (State::None, Pipe::Ground) => {
                    if inside {
                        n += 1;
                    }
                }
                (State::None, Pipe::Vert) => {
                    inside = !inside;
                }
                (State::None, Pipe::Se) => {
                    state = State::South;
                }
                (State::None, Pipe::Ne) => {
                    state = State::North;
                }

                // Horizontal lines make no difference to anything
                (State::North | State::South, Pipe::Horiz) => {}

                // U-turns
                (State::South, Pipe::Sw) | (State::North, Pipe::Nw) => {
                    state = State::None;
                }

                // Form a vertical line
                (State::South, Pipe::Nw) | (State::North, Pipe::Sw) => {
                    inside = !inside;
                    state = State::None;
                }

                _ => {
                    panic!("Unexpected sequence {state:?} {pipe:?}");
                }
            }

This is the exact same thing except you're visiting two arguments at a time.

Guess what, the same syntax I gave supports exactly that as well.