Test of Tuple Operators

tuple-test.ts

type TestTuple = [
  "key1",
  "union type 1" | "union type 2" | "union type 3",
  "key2",
  string,
  "key3",
  number,
  "key4",
  [string, number, null | string]
];

type TestSlicedTuple = SliceTuple<TestTuple, 2>; 
// result is [["key1", "union type 1" | "union type 2" | "union type 3"], ["key2", string], ["key3", number], ["key4", [string, number, string | null]]]

type TestSlicedTupleItem = TestSlicedTuple[0];
// result is ["key1", "union type 1" | "union type 2" | "union type 3"]

type TestListToTypeAlias = MergeTuple<TestSlicedTuple>; 
// result is [string, number, string | null]; & {key3: number;} & {key2: string;} & {key1: "type 1";};
// result is equal to {key4: "an another type"; key3: number; key2: string; key1: "type 1";}

type TestListToUnion = PipeTuple<TestSlicedTuple>; 
// result is [] | ["key1", "union type 1" | "union type 2" | "union type 3"] | ["key2", string] | ["key3", number] | ["key4", [string, number, string | null]]

type TestAlias = TestListToTypeAlias["key4"]; 
// result is [string, number, string | null]

type TestKeys = TestListToUnion[0]; 
// result is "key1" | "key2" | "key3" | "key4" | undefined

type TestTypes = TestListToUnion[1]; 
// result is string | number | [string, number, string | null] | undefined