Add TS typings

[yenbekbay]

Note: these typings will only work with TS 2.8+, as they make use of Conditional types to infer the return types of async functions.

[developit]

@yenbekbay It might be wise to hold off on merging typings that require 2.8+ at this point. I think a lot of people are still on 2.7, myself included (2.8 is broken on my projects).

I wonder - do you think it'd be worth doing a PR without the conditional types in the interim?

FWIW I've picked up TypeScript now and would be happy to hack on porting this library over to be written in TS if that's interesting to you.

[fimars]

Maybe you can first publish a @types version? @yenbekbay

[CTOlet]

@fimars When will you accept whit PR? Very useful

[fimars]

@nemmo I am not maintaining this project. This PR is as @developit said, some of the broken changes may not be merged now. Maybe you can make a new PR. 🤔

[CTOlet]

There is no any broken changes cause it is just typing definitions that allows to use that library in TypeScript projects.

[fimars]

It might be wise to hold off on merging typings that require 2.8+ at this point. I think a lot of people are still on 2.7, myself included (2.8 is broken on my projects).

I wonder - do you think it'd be worth doing a PR without the conditional types in the interim?

@nemmo author said.

[developit]

Is there a way to avoid having to cap the list here?

[yenbekbay]

In fact, yes, but only if we use rest parameters instead of a single list parameter.

With the introduction of rest parameters with tuple types in TypeScript 3.0 and mapped types on tuples in TypeScript 3.1, we can simplify the type definition for the parallel method to this:

series<T extends any[]>(
  ...list: T
): Promise<{[K in keyof T]: AsyncFnReturnType<T[K]>}>;

But then, it's probably not an option to change the function signature.

---

However, with the introduction of optional elements in tuple types in TypeScript 3.0, we can get rid of overloads and reduce the method's type definition to:

series<
  T extends [any, any?, any?, any?, any?, any?, any?, any?, any?, any?]
>(
  list: T,
): Promise<{[K in keyof T]: AsyncFnReturnType<T[K]>}>;

Then, we can increase the capping to a higher number of elements (by adding extra any? elements to the generic tuple type) without adding a ton of overloads.

[darkbasic]

@developit @yenbekbay any chance to get a new version with the updated typings? This is really a blocker for those who use Typescript :(

[fimars]

TypeScript is version 3.7 now. Maybe we can do something.

cc @developit