AI solution for TypeScript puzzle on BFE.dev
18. implement TupleToUnion<T>

type TupleToUnion<T extends any[]> = T[number];

Explanation:

• T is a generic parameter that extends an array of any type T extends any[].
• T[number] returns a union type of all the elements of the tuple T.

For example, given type Foo as [string, number, boolean], T will be inferred as [string, number, boolean], and T[number] will be "string" | number | boolean, which is the expected union type.