curry.js

const discount1 = (price, discount) => {
  const final = price * (1 - discount);
  console.log(`V1 -- Original Price: ${price}, Discount: ${discount}, Final Price: ${final}`);
}

discount1(500, 0.5);
discount1(400, 0.5);
discount1(300, 0.5);

const halfPrice1 = price => discount1(price, 0.5);

halfPrice1(500);
halfPrice1(400);
halfPrice1(300);

const discount2 = discount => price => {
  const final = price * (1 - discount);
  console.log(`V2 -- Original Price: ${price}, Discount: ${discount}, Final Price: ${final}`);
}

const halfPrice2 = discount2(0.5);
// const halfPrice2 = price => discount2(0.5)(price);

halfPrice2(500);
halfPrice2(400);
halfPrice2(300);

https://jsbin.com/novoduq/1/edit?js,console