Typescript type for just-partition does not narrow type correctly when using a type guard

[vidhill]

The Typescript type for just-partition does not narrow type correctly when using a type guard

I'm not sure what the best way to report/describe TS issues, so I will use screenshots,
I hope that that is okay,

In contrast with how using Array.filter() correctly narrows the type

The type returned from partition, when using the example type guard, is a tuple of unions of the possible values

[PromiseRejectedResult | PromiseFulfilledResult<boolean>, PromiseRejectedResult | PromiseFulfilledResult<boolean>]

What I would really like/expect is that the types would be correctly inferred, in the same way that Array.filter() does

[ PromiseFulfilledResult<boolean>, PromiseRejectedResult ]

I can work around this by casting the result, but that is not ideal

I have a suggested fix, using a function Type override

I will open a PR,

I just wanted to link the PR to an issue

[vidhill]

- I edited above for (hopefully) more clarity