A subtype in a list is not a subtype?

[sharno]

According to the Subtypes page in Flow documentation about Subtypes, that works fine:

type A = {+id: number}
type B = {+id: number, +text: string}

const b : B = {id: 1, text: "hello"}
const a : A = b

but why when we put the types in a list it loses the property of being a subtype?

type A = {+id: number}[]
type B = {+id: number, +text: string}[]

const b : B = [{id: 1, text: "hello"}]
const a : A = b

And is there a cleaner way of solving such an issue if I want to pass B as an array to a function that takes A as an array without casting to any first?

https://flow.org/try/#0C4TwDgpgBAglC8UDeBqAlgEwFxQHYFcBbAIwgCcBfAbQF0AoUSKAIQWXWzyNLIBooUwCAA9gOAM7AyaXAHNq9OgGMA9rklRiUHK0RUkmHAEZ+Q0TgBEACwgAbWyosV6q9cCgBDbbDbE6QA

[apsavin]

Like this: https://flow.org/try/#0C4TwDgpgBAglC8UAkAlCBDAJgeQHYBsQYAnY9EAHgG8BqAS0wC4pcBXAWwCMJiBfAPgBQoSFABCCKLQbM2XHgBooNYBAAewZgGdgxOrgDmvANoBdQYIDGAe1w6onKMwmJjVGVACMS1RuYAiAAsIfHxrf15zGztgKHQnWElOQSA

[TrySound]

This probably can be closed.
/cc @vkurchatkin

[sharno]

Thanks!
Is there an issue tracking the $ReadOnlyArray getting documented? As it's not in the documentation yet

[apsavin]

#2464