TypeScript: Union to Intersection

union_to_intersection.ts

/**
 * An efficient TypeScript utility type to transform a union of objects into the intersection of such objects.
 * 
 * - TypeScript 5.8.2
 * - Benchmarked against the similar type declared at [utility-types](https://github.com/piotrwitek/utility-types):
 *      - `utility-types`: ~250ms
 *      - `this`: ~30ms
 * 
 * - This haven't been deeply tested for correctness yet.
 */

type UnionToIntersection<T> = { [K in T as K & string]: K }[any]

/** 
 * Benchmark
 * (Benchmark was performed with a custom tool I haven't published yet,
 * the used types are described below for reproducing with other tools)
 */

type Union =
    (() => void)
    | ((a0: string) => void)
    | ((a0: string, b0: number) => { c0: boolean })
    | { b0: number, c0: string }
    | ({ d0: boolean, e0: Date } & { f0: number })
    | { g0: string[] }
    //
    // | [1...19]
    //

type utilityTypes_UnionToIntersection<T> = (T extends any
    ? (k: T) => void
    : never) extends (k: infer I) => void
      ? I
      : never;

// @ts-benchmark(this version)
type Intersection = UnionToIntersection<Union>
// @ts-benchmark(utility-types version)
type utilityTypes_Intersection = utilityTypes_UnionToIntersection<Union>

type IsSimilar = 
    (Intersection extends utilityTypes_Intersection ? 'yes' : 'no')
    | (utilityTypes_Intersection extends Intersection ? 'yes' : 'no')