# * Primitive types

let foo: string = "Hello";

let bar: number = true; //TS2322: Type 'true' is not assignable to type 'number'.

//함수 선언식
function multiply(x: number, y: number) {
  return x * y;
}

//함수 표현식
const multiply2 = (x: number, y: number): number => x * y;
const multiply3 = (x: string, y: number): number => x * y;

console.log(multiply(10, 5));
console.log(multiply2(8, 3));
console.log(multiply2(true, 1)); //error TS2345: Argument of type 'true' is not assignable to parameter of type 'number'.
console.log(multiply3('foo', 1)); //error TS2362: The left-hand side of an arithmetic operation must be of type 'any', 'number', 'bigint' or an enum type.