when R.binary function is used ?

[coleea]

I understand R.Binary's spcification from https://ramdajs.com/docs/#binary .

But I don't know what situation I use this for. I think It was made because it's useful.

It is good if someone give me an example.

Thank you.

[kedashoe]

Not very often, I would say 😛 But basically, if you are calling a function that takes however many arguments, you can use unary, binary, nAry to create a new function that takes exactly how many arguments you want. An example with unary

let xs = ["1", "2", "3"];
console.log(xs.map(parseInt)); // => [1, NaN, NaN]
console.log(xs.map(R.unary(parseInt))); // => [1, 2, 3]

[FernandoBasso]

Nice @kedashoe. Thanks for the example, which is a practical one indeed.

Let's see if maybe more people come up with practical/real life examples, maybe also one really using binary.

[coleea]

thank you for explanation.

in summary, unary, binary, and nAry is used for function that's arity varies ?

for example, I made a function that receives 3 parameters. and 2nd, 3rd argument is optional

in this case, the function operates differently depends on the number of parameters.

R.binary is used for this situation.

If I am wrong, please point it out.

thank you again