Type Selection Queries

This might be a bit of a crazy idea, but here goes: to enable loose coupling between components we sometimes write Pick<Type, 'a' | 'b' | 'c'>

It would be nice if we could create a type query to select properties with a similar syntax to GraphQL:

e.g:

prop: AType[{a, b, c: { d }]

This would be equivalent to

prop: Pick<AType, 'a' | 'b'> & {c: Pick<AType['c'], 'd'>}

How often would you do that in "the real world" ? definitely more often if you could
How often should you do that? unclear ?

Some real-world code:

    const testFetch = jest.fn()

    class TestOptions extends GraphQlClient.Options {
      public fetch = testFetch
    }
    const response: Pick<Response, 'ok' | 'json'> = {
      ok: true,
      async json() {
        return { data: { auth: { token: testToken } } }
      }
    }
    testFetch.mockResolvedValue(response)

Pick<Response, 'ok' | 'json'> could be Response[{ok, json}]

edit: that's not a great example use case, cause you could just as well do Partial<Response>

まず、TypeScript における既存の Pick と indexed-access type の挙動を調査し、次に提案されているネストされた選択構文を GraphQL 形式のクエリと比較します。issue の例を確認し、この機能に明確なユースケースと型システムの設計があるかどうかを判断します。完了とするには、単なる変換例ではなく、合意された構文、セマンティクス、実装計画が必要です。