Reuse instances of case classes

Question

Suppose my application uses a lot of Move objects over and over durring a long period of time, where Move is defined as follows:

sealed trait Player
case object P1 extends Player
case object P2 extends Player
case object P3 extends Player
case object P4 extends Player

sealed trait Key
case object Up extends Key
case object Down extends Key
case object Right extends Key
case object Left extends Key
case object Space extends Key

sealed trait Action
case object Press extends Action
case object Release extends Action

case class Input(key: Key, action: Action)
case class Move(input: Input, player: Player)

That's 10 different possible Inputs, and 40 different Moves. Is there a way to ask the compiler to optimise these types by creating all the possible Moves once and reusing the instances over time?

Answer 1

You could use a scalaz Memo:

val moveCache = Memo.mutableHashMapMemo{ip: (Input, Player) => Move(ip._1, ip._2)}
....
val myMove = moveCache((myInput, myPlayer))

Honestly I very much doubt this would have a significant effect on performance. Before making your code less readable, make sure you have clear profiling results that show that it actually makes the difference you think.