[Typescript Challenges] 8. Easy - If

Implement a utils If which accepts condition C, a truthy return type T, and a falsy return type F. C is expected to be either true or false while T and F can be any type.

For Example:

type A = If<true, 'a', 'b'>  // expected to be 'a'
type B = If<false, 'a', 'b'> // expected to be 'b'

 

/* _____________ Your Code Here _____________ */

type If<C extends boolean, T, F> = C extends true ? T: F;


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

type cases = [
  Expect<Equal<If<true, 'a', 'b'>, 'a'>>,
  Expect<Equal<If<false, 'a', 2>, 2>>,
]

// @ts-expect-error
type error = If<null, 'a', 'b'>