Il fût un temps où l'on écrivait
le temps des closures
// A function that generators a new function for adding numbers
function addGenerator( num ) {
// Return a simple function for adding two numbers
// with the first number borrowed from the generator
return function( toAdd ) {
return num + toAdd
};
}
// addFive now contains a function that takes one argument,
// adds five to it, and returns the resulting number
var addFive = addGenerator( 5 );
// We can see here that the result of the addFive function is 9,
// when passed an argument of 4
alert( addFive( 4 ) == 9 );
le temps des blocs
let addFive_b;
{
let five = 5;
addFive_b = function ( toAdd ) {
return five + toAdd
};
}
console.log(addFive_b( 4 ) == 9 );
Le temps des arrow functions
ES6 arrow functions make it easy to write curried functions manually:
const add = x => y => x + y;
That means that you have to invoke
add() as follows:add(5)(4); // 9
This is currying: a function with an arity greater than one becomes a nested series of functions. Most functional programming languages with automatic currying have syntax where there is no difference between
add(1, 2) and add(1)(2).