Extract type of last element of tuple in TypeScript

Essentially, what I am trying to write is a function that accepts an array of different types, (do something with that), and then return a type based on only the last element in that array (previous elements have been processed, but only the last element is used for the return value).

I know I can write a function that returns an array based off of all element types as follows.

function arraymod<T extends unknown[]>(
  ...input: {
    [index in keyof T]: ParamType<T[index]>
  }
): T {
  return input.map(unparam);
}

What I want is a function that does something like this.

function takelast<T extends unknown[]>(
  ...input: {
    [index in keyof T]: ParamType<T[index]>
  }
): LastElementOf<T> /* What would this return type be? */ {
  return unparam(input[input.length - 1]);

(ParamType<T> and unparam are just some example types/functions for illustration)

How can I write a type LastElementOf<T> that gives the type of the last element of a tuple T (or array, eventhough that would just be type of any element).

We must use infer keyword to achieve this result.

We are going to check the array to extend infer last item and the rest of them, which we don't care about:

type LastElementOf<T extends readonly unknown[]> = T extends readonly [...unknown[], infer Last]
  ? Last
  : never;

...unknown[] will be first items except the last one, and the last one will be the infer Last

Usage:

type Case1 = LastElementOf<[]>; // never
type Case2 = LastElementOf<['dasd']>; // "dasd'
type Case3 = LastElementOf<['string', 12, false]>; // false
type Case4 = LastElementOf<readonly ['string', 12, false]>; // false

playground