863329 - Implement `partialRight` on `sdk/lang/functional`

Status: RESOLVED WONTFIX

(Add-on SDK Graveyard :: General, defect)

Description

[Matteo Ferretti [:zer0] [:matteo]]

Partially related to bug 863315: in IRC Irakli agreed about the refactoring of `sdk/event/utils`, and also pointed out some interesting use of having a partial application of those function that bound the `callback` instead of the `target`.

That could be actually useful in general, even in the standard generics where the `callback` is the second / last argument. We should have a `partial` function that returns a new function with the arguments bound starting from the right, instead of the left.

Comment 1

[Matteo Ferretti [:zer0] [:matteo]]

Irakli, I'd like to have your feedback about it. How do you think it should logically behaves? For example, let's having a `log` function with three arguments:

    function log(a, b, c) {
        console.log(a, b, c);
    }

And then:

    let plog = partialRight(10);

What should be the output in those cases?

    plog();
    plog(1);
    plog(1, 2);
    plog(1, 2, 3);

We can approach in at least two / three different ways, and you have more experience in other functional languages, so maybe you have some good suggestion about it.

Comment 2

[Matteo Ferretti [:zer0] [:matteo]]

of course it is `plog = partialRight(log, 10)`.

Comment 3

[Irakli Gozalishvili [:irakli] [:gozala] [@gozala]]

Most functonal js libs expose something function called `flip` that just returns fn with flipped args, so you could use same partial there too. I think that's a way to go, although I'd close this as won't fix until we actually need this.

Comment 4

[Irakli Gozalishvili [:irakli] [:gozala] [@gozala]]

Let's reopen when we'll actually need such an utility, so far need for this is just theoretical.