5z11-type-level-typescript-9장-문제

/**
 * `Pick` is a built-in helper function that takes an object type
 * `Obj`, an arbitrary type `T` and removes any keys from `Obj`
 * that aren't assignable to `T`.
 *
 * Try to implement your own version of it!
 */
namespace pick {
  type MyPick<Obj, T> = {
    [K in Extract<keyof Obj, T>]: Obj[K]
  };
 
  type res1 = MyPick<{ a: string; b: number; c: boolean }, "a">;
  type test1 = Expect<Equal<res1, { a: string }>>;
 
  type res2 = MyPick<{ a: string; b: number; c: boolean }, "a" | "b">;
  type test2 = Expect<Equal<res2, { a: string; b: number }>>;
 
  type res3 = MyPick<{
    getName: () => string;
    setName: (x: string) => void;
  }, `get${string}`>;
  type test3 = Expect<Equal<res3, { getName: () => string }>>;
}