Question about Option type guards

Hi 👋

A belt port in TS is something I’ve already dreamed of, so thank you! I tried adding it to our codebase, but think it might have an issue with the Option type guards (isSome / isNone)

On usage with ts-pattern (for pattern maching):

import { A, O } from "@mobily/ts-belt";
import { match, when } from "ts-pattern";

const array = A.make(Math.floor(Math.random() * 10), "foo");

match(A.get(array, 5))
  .with(when(O.isSome), value => { /* value is O.Option<string>, it should be string */ })
  .with(when(O.isNone), value => { /* value is O.Option<never>, it should be never */ })
  .exhaustive();

I checked the types of the given function and it confirms the issue:

/** Returns `true` if the provided `option` is `Some(value)`, otherwise, returns `false`. */
export declare function isSome<T>(option: Option<T>): option is Option<T>;

/** Returns `true` if the provided `option` is `None`, otherwise, returns `false`. */
export declare function isNone<T>(option: Option<T>): option is Option<never>;

Shouldn’t it returns option is T and option is never instead?

Same example with Rescript (v is int, not option(int)):

https://rescript-lang.org/try?code=DYUwLgBAtgngcgV2MAhgI1ANRcBIIC8EAygPZQgAUArAJQBQ9AzgO4CWYAxgBbTxKoMIbLnwBvegB8S5KgDdahAHwQAUkwB0wUgHMATJQBEcnHghsmEAA4AnEExAA7MIYA0EBVIhxSj-ARV1LV0jE1FzS3QHZ0MGAF96IA

[mobily]

@zoontek the Option type is now type Option<T> = T | undefined | null, this change has been published in v3.8.0 🚀 thanks for all your help and valuable suggestions, I really appreciate that! ❤️

[zoontek]

I will check a bit longer to see if I can create ts-pattern guard, I don’t want to lose pattern matching (I think you understand that 😄) I close this issue, will publish a comment if I find something.