type-challenges-solutions/en/easy-parameters

[utterances-bot]

Parameters

This project is aimed at helping you better understand how the type system works, writing your own utilities, or just having fun with the challenges.

https://ghaiklor.github.io/type-challenges-solutions/en/easy-parameters.html

[AurelienWebnation]

Hey!

Maybe we can add

type MyParameters<T extends Function> = ...

[ghaiklor]

@AurelienWebnation Personally, I don't see the reason for that because we check it with conditional type anyway…

[AurelienWebnation]

type MyParameters<T> = T extends (...args: infer P) => any ? P : never;
type Foo = MyParameters<string>; // Foo = never

type MyParameters<T extends Function> = T extends (...args: infer P) => any ? P : never;
type Foo = MyParameters<string>; // Error on string : Type 'string' does not satisfy the constraint 'Function'

So the second solution is an alternative to have an error directly on My Parameters type if we don't pass a function. But it's just an idea ahah!