The arity of a function is the number of arguments it requires. Currying a function means to convert a function of N arity into N functions of arity 1.
In other words, it restructures a function so it takes one argument, then returns another function that takes the next argument, and so on.
Here's an example:
//Un-curried function
function unCurried(x, y) {
return x + y;
}
//Curried function
function curried(x) {
return function(y) {
return x + y;
}
}
//Alternative using ES6
const curried = x => y => x + y
curried(1)(2) // Returns 3
This is useful in your program if you can't supply all the arguments to a function at one time. You can save each function call into a variable, which will hold the returned function reference that takes the next argument when it's available. Here's an example using the curried function in the example above:
// Call a curried function in parts:
var funcForY = curried(1);
console.log(funcForY(2)); // Prints 3
Similarly, partial application can be described as applying a few arguments to a function at a time and returning another function that is applied to more arguments.
Here's an example:
//Impartial function
function impartial(x, y, z) {
return x + y + z;
}
var partialFn = impartial.bind(this, 1, 2);
partialFn(10); // Returns 13
Заполните тело функции add чтобы он использовал currying для добавления параметров x , y и z .