GraphQL API Design Interview Question

_Prompt.md

I'm designing a stream API in GraphQL and having trouble choosing between the two implementations below. Which would you choose and why is it a better choice?

A.graphql

stream {
  ... on Text {
    html
  }
  ... on Photo {
    url
  }
  ... on CodeSnippet {
    embedSrc
  }
  ... on CodeExample {
    embedSrc
  }
}

B.graphql

stream {
  textSnippets {
    createdAt
    html
  }
  photos {
    createdAt
    url
  }
  codeSnippets {
    createdAt
    embedSrc
  }
  codeExamples {
    createdAt
    embedSrc
  }
}

ExampleAnswer.md

Yeah, the first is definitely more "correct." Why? because the API is designed to return a stream, and a stream is a list of stream items in a certain order that happens to be one of those types. The stream determines what the order is. The second moves the responsibility for determining what a stream is to the receiver. I'd need to construct a "stream" by knowing what item types are in a stream and cobbling them together. I might as well have this and drop all pretext of the API determining what a stream is:

            createdAt
            html
          }
          photos {
            createdAt
            url
          }
          codeSnippets {
            createdAt
            embedSrc
          }
          codeExamples {
            createdAt
            embedSrc
          }```