It was would be nice for this to be automatic but filter does work like this it you pass a type guard as the predicate: ``` arr.filter((a: A): a is A & { kind:

It was would be nice for this to be automatic but filter does work like this it you pass a type guard as the predicate: ``` arr.filter((a: A): a is A & { kind: 'bar'} => a.kind === 'bar') ``` If you define: ``` function isKind<K extends A['kind']>(kind: K): (a: A) => a is A & { kind: K } { return (a): a is A & { kind: K } => a.kind === kind; } ``` Then you can write: ``` arr.filter(isKind('bar')) ``` and get a properly narrowed return type array