Would It Be Possible to Update the Typing of max([0, anyNumber]) Such That It Returns Number?

[klondikemarlen]

Context

Would it be possible to update the typing of max([0, someNumberVariable]) such that it returns number?

Given this Typescript code

max([0, someNumberVariable])

I would expect the type to be a number.
Instead the type is number | undefined
So in practice, I need to write the function as

max([0, someNumberVariable]) as number

I've done weirder things with TypeScript in the past, so it seems likely that this would be possible, but I can't even find the definition of max in the Lodash repo, so I might not be correct.

[klondikemarlen]

After much digging, I found a definition of max, but I don't know if it is the only definition https://github.com/lodash/lodash/blob/4.0.1-npm-packages/lodash.max/index.js

[klondikemarlen]

Some kind of overload like

function max(array: []): undefined;
function max(array: number[]): number;
function max(array: number[]): number | undefined {
  return (array && array.length)
    ? baseExtremum(array, identity, baseGt)
    : undefined;
}

const foo = max([4, 2, 8, 6]) // is number
const bar = max([]) // is undefined

might work?

[klondikemarlen]

Or something like this?

type NonEmptyArray<T> = [T, ...T[]];

function max<T>(array: NonEmptyArray<T>): T;
function max<T>(array: T[]): T | undefined;
function max<T>(array: T[]): T | undefined {
  return (array && array.length)
    ? baseExtremum(array, identity, baseGt)
    : undefined;
}

const foo = max([4, 2, 8, 6]) // number
const bar = max([]) // undefined
const baz = max([[]]) // never[] - I don't even know what that means ...