All CLA requirements met.

Hi, this is a really good initiative, do you think we can skip specifying generic after this
#30215 is merged?

@typescript-bot test this

Heya @RyanCavanaugh, I've started to run the extended test suite on this PR at 24e7e1c. You can monitor the build here. It should now contribute to this PR's status checks.

@beshanoe I think that may be sufficient to allow us to skip specifying generic parameters. I'm not sure though without testing it.

I found:

function B<T>(value: T): value is Exclude<T, false | null | undefined | '' | 0> {
  return Boolean(value);
}

was already sufficient, but adding prototypes/new functions to the interface forces you to be explicit.

@ForbesLindesay can you merge this up with master? This will allow us to re-run the RWC suite to evaluate the effects of this on our real-world code database

@RyanCavanaugh sorry I didn't see your message. I've merged it now.

@RyanCavanaugh any update on this?

@typescript-bot test this

Heya @RyanCavanaugh, I've started to run the extended test suite on this PR at 37bb42c. You can monitor the build here. It should now contribute to this PR's status checks.

RWC is actually clean, ignore ❌

@RyanCavanaugh any chance we can merge this? It's been a while and it's a very simple fix.

@RyanCavanaugh any chance we can merge this? It's been a while and it's a very simple fix.

☝️ 🙏

Resolves #31164.

broken by #31515

This would be a great addition to the language. Have there been any plans on when it might land? 3.8 maybe?

@city41 Unfortunately it is still open #16655 Really strange thing, that behaviour of !!someValue differs from Boolean(someValue)

@RyanCavanaugh

Can we revive this. Still continues to prevent usage of the .filter(Boolean) syntax sugar today.

@RyanCavanaugh

Can we revive this. Still continues to prevent usage of the .filter(Boolean) syntax sugar today.

Check out ts-reset.

Is there a good workaround in the meantime? I'm not sure how else to express .filter(Boolean) in a way Typescript accepts.

Is there a good workaround in the meantime? I'm not sure how else to express .filter(Boolean) in a way Typescript accepts.

You can use type guards:

["", undefined, "test"].filter((x): x is string => typeof x === "string")

Playground Link

.filter((x): x is NonNullable<typeof x> => Boolean(x))

Works universally for any Array<T>

.filter((x): x is NonNullable<typeof x> => Boolean(x))

Works universally for any Array<T>

The code in #29955 (comment) more completely shows the result of Boolean excludes other falsey values