599-merge.ts

/**
 * 599 - Merge
 *
 * Merge two types into a new type. Keys of the second type overrides keys of the first type.
 *
 * For example
 *
 * ```ts
 * type foo = {
 *   name: string
 *   age: string
 * }
 * type coo = {
 *   age: number
 *   sex: string
 * }
 *
 * type Result = Merge<foo, coo> // expected to be {name: string, age: number, sex: string}
 * ```
 */

/* _____________ Your Code Here _____________ */

type Merge<F, S> = {
  [K in (keyof F | keyof S)]: K extends keyof S
    ? S[K]
    : K extends keyof F
      ? F[K]
      : never;
}

/* _____________ Test Cases _____________ */
import type { Equal, Expect } from '@type-challenges/utils'

type Foo = {
  a: number
  b: string
}
type Bar = {
  b: number
  c: boolean
}

type cases = [
  Expect<Equal<Merge<Foo, Bar>, {
    a: number
    b: number
    c: boolean
  }>>,
]