Q32. What is currying in JavaScript?

// সাধারণ ফাংশন
function addThree(a, b, c) {
  return a + b + c;
}

// curried সংস্করণ
function curriedAdd(a) {
  return function (b) {
    return function (c) {
      return a + b + c;
    };
  };
}

curriedAdd(1)(2)(3); // 6

const add = (a) => (b) => (c) => a + b + c;

console.log(add(1)(2)(3)); // 6

// map-এর সাথে দারুণ কাজ করে
const users = [
  { name: "Rahim", age: 25 },
  { name: "Karim", age: 30 },
];

const getName = (obj) => obj.name;

console.log(users.map((user) => getName(user))); // ["Rahim", "Karim"]

function greet(greeting) {
  return function (name) {
    return greeting + ", " + name + "!";
  };
}

// শুধু অংশটা তৈরি, পরে ব্যবহার
const hello = greet("হ্যালো");
const goodMorning = greet("সুপ্রভাত");

console.log(hello("Rahim"));      // "হ্যালো, Rahim!"
console.log(goodMorning("Karim")); // "সুপ্রভাত, Karim!"

// লজিক আলাদা করা
const withTax = (rate) => (price) => price * (1 + rate);
const withDiscount = (rate) => (price) => price * (1 - rate);

console.log(withTax(0.1)(100));    // 110.00000000000001
console.log(withDiscount(0.2)(100)); // 80