OnceMoreImplicits.scala

OnceMoreImplicits.scala

// this compiles and finds all implicits,
// so no clue why it doesn't work in the real case

trait _Var[ Tx, A ]

trait Sys[ S <: Sys[ S ]] {
   type Tx
   type Var[ A ] <: _Var[ S#Tx, A ]
   def atomic[ A ]( fun: S#Tx => A ) : A
}

trait KSys[ S <: KSys[ S ]] extends Sys[ S ] {
   def root[ A ]( init: => A )( implicit tx: S#Tx, ser: Serializer[ S#Tx, A ]) : A
}

trait Serializer[ -Tx, A ]

trait Mutable[ S <: Sys[ S ]]

trait MutableSerializer[ S <: Sys[ S ], A <: Mutable[ S ]] extends Serializer[ S#Tx, A ]

def whatever[ Tx, A ] = new Serializer[ Tx, A ] {}

implicit def option[ Tx, A ]( implicit peer: Serializer[ Tx, A ]) : Serializer[ Tx, Option[ A ]] = whatever

implicit def varSer[ S <: Sys[ S ], A ]( implicit peer: Serializer[ S#Tx, A ]) : Serializer[ S#Tx, S#Var[ A ]] = whatever

trait Test[ S <: KSys[ S ]] {
   def s: S
    
   object Node {
      implicit object ser extends MutableSerializer[ S, Node ] {
      }
   }
   trait Node extends Mutable[ S ]
   
   s.atomic { implicit tx =>
      s.root[ S#Var[ Option[ Node ]]]( sys.error( "TODO" ))
   }
}