Typed API 2.0 - Record as TypedMap, ColumnDef with covariant T

[CodeLionX]

Proposed Changes

Reasonable Implementation of Record

• Map-like implementation heavily based on scala.collection API
• TypedMap as a base-implementation for maps with key/value bindings, where the key contains type-information about the value
  • access with a typed key can only return a value of the right type
  • API defined in TypedMapLike, eg.

  • TypedMapLike[K[+_ <: V], V, This <: ...]#apply[T <: V](k: K[T]): T

  • same applies now for Records as they implement TypedMapLike
• no more // FIXME or unimplemented methods!
• changes to ColumnDef were necessary:
  • TypedMapLike defines its key's type-parameter covariant: K[+_ <: V] (semantic of maps!)
  • therefore, type-parameter of ColumnDef[T] must be changed to be covariant, too: ColumnDef[+T]
  • this does not fit to our definition of a UntypedColumnDef anymore as it contained a type-parameter, which is per definition invariant
  • new type-alias: ColumnDef.UntypedColumnDef = ColumnDef[Any] can be seamlessly substituted for the old class
• out of strange reasons (I don't know them, yet), we now have to define columns via:

  val col: ColumnDef[Int] = ColumnDef[Int]("col_name")
  val col = ColumnDef[Int]("col_name")

  otherwise scalac does not find the right implicit for the default value. Call the ColumnDef-factory always with explicit type-parameter!

[CodeLionX]

Codacy is not working! :disappointed:

[CodeLionX]

@srfc please review PR #102 as this one is already closed. It contains the changes you requested!