infer.ts

function add(a: number, b: number): number {
  return a + b;
}

type Test = typeof add;
// ^ = type Test = (a: number, b: number) => number
type Test2 = ReturnType<typeof add>;
// ^ = type Test2 = number
//

type MyReturnType<T> = T extends (...args: any[]) => infer R ? R : any;
type Test3 = MyReturnType<typeof add>;
// ^ = type Test3 = number
//
//