Extracting Arguments type of an abstract action executor method

functionArgumentsType.ts

// Class-based Tree Shaking - HTTP203 @ Google Chrome Developers
// https://www.youtube.com/watch?v=lsd2-TCgHEs&t=599

class Store {
  /**
   * Do the given action with the given parameters.
   *
   * @param {A => R} action Action to be taken.
   * @param {A} args Arguments to be passed to the action.
   * @returns {R} Returns the result of original action call.
   */
  public do<A extends any[], R>(
    action: (...args: A) => R,
    ...args: A
  ): R {
    return action.apply(this, args);
  }
}

const set = (prop: string, value: number) => `Set ${prop} = ${value}`;
const get = (prop: string) => 42;

/* ------- */

const store = new Store();

let v = store.do(set); // ...args: [string, number]    => string
let g = store.do(get); // ...args: [string]            => number