Allow index() within type definitions

[lukepighetti]

We are allowed to use 'validate', 'read', 'write', 'create', 'update', 'delete' but not index() within type definitions. It would be nice to be able to specify the index at the type level and have that index apply anywhere it is used.

Another reason is to tightly couple indexing to the type schema.

[lukepighetti]

Currently

path /reviews/{pid}/{rid} is Review {
  read() { isSignedIn() }
  write() { isCurrentUser(uid) }

  index() { ["score"] }

  path /spacesuitx {
    index() { ["s","p","a","c","e","z","u","i","t","x"] }
  }
}


type SpacesuitX {
  /// 42 bytes
  /// 65% reduction with one letter keys
  s: Score | Null,
  p: Score | Null,
  a: Score | Null,
  c: Score | Null,
  e: Score | Null,
  z: Score | Null,
  u: Score | Null,
  i: Score | Null,
  t: Score | Null,
  x: Score | Null,

}

Proposed

path /reviews/{pid}/{rid} is Review {
  read() { isSignedIn() }
  write() { isCurrentUser(uid) }

  // Review contains type SpacesuitX
}


type SpacesuitX {
  /// 42 bytes
  /// 65% reduction with one letter keys
  s: Score | Null,
  p: Score | Null,
  a: Score | Null,
  c: Score | Null,
  e: Score | Null,
  z: Score | Null,
  u: Score | Null,
  i: Score | Null,
  t: Score | Null,
  x: Score | Null,

  index() { ["s","p","a","c","e","z","u","i","t","x"] }
}