Proposal: Promisable

[fabiospampinato]

Some times we are just awaiting a function, so we don't really care if the returned value is actually a promise or not. With Promisable:

type Promisable<T> = T | Promise<T>;

One could write this:

type Foo = () => Promisable<string | number | null>

Rather than:

type Foo = () => string | number | null | Promise<string> | Promise<number> | Promise<null>

It helps write a bit cleaner code. I'm not sure if it's useful enough to be included here, but I thought I'd mention it.

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[kainiedziela]

I'd be happy to integrate this.

[WORMSS]

This could also be quite nice for Promise.all style arguments.

[sindresorhus]

Accepted on the condition that someone opens an issue on TypeScript requesting it be added as a built-in, and comments the link to the issue here. I think it's a very common need.

For anyone that wants to tackle this, please read guide for adding a type and also see how the last type was added: 22c3a99 (Note the extensive docs and comments).

[fabiospampinato]

Accepted on the condition that someone opens an issue on TypeScript requesting it be added as a built-in, and comments the link to the issue here. I think it's a very common need.

👍 microsoft/TypeScript#32220

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Edit: there was already an issue about this: microsoft/TypeScript#31394