如何在 typescript 中检索 function 签名列表？

Question

I have a function

function add (...nums: number[]): number {
  return nums.reduce((a, b) => a + b)
}

how do I grab this signature? so that I can use it here

function subtract (
  sum: ReturnType<add>, 
  ...args: [/* <-- Here I want to grab the same type as add's arguments */]
): number {
  return args.reduce((running, next) => running - next  , sum)
}

Answer 1

I would go with Parameters

Parameters<T>

Constructs a tuple type of the types of the parameters of a function type T.

function subtract (
  sum: ReturnType<typeof add>, 
  ...args: Parameters<typeof add>
): number {
  return args.reduce((running, next) => running - next  , sum)
}