https://en.wikipedia.org/wiki/Trampoline_(computing)

trampoline.ts

type NotFunction =
  | string
  | number
  | boolean
  | null
  | undefined
  | bigint
  | readonly any[]
  | { apply?: never; [k: string]: any }
  | { call?: never; [k: string]: any };

export type Trampoline<T extends NotFunction> = T | (() => Trampoline<T>);

export type TrampolineFunc<A extends any[], T extends NotFunction> = (
  ...args: A
) => Trampoline<T>;

export function trampoline<A extends any[], T extends NotFunction>(
  fn: TrampolineFunc<A, T>
) {
  return (...args: A) => {
    let result = fn(...args);
    while (typeof result === "function") {
      result = result();
    }
    return result;
  };
}

/* -------------------------- */

function factorialImpl(n: number, prev: number = 1): Trampoline<number> {
  if (n < 2) return prev;
  return () => factorialImpl(n - 1, prev * n);
}

const factorial = trampoline(factorialImpl);

console.log(factorial(1000));