ComposeEithers.scala

   
    type Result[A] = Either[ Seq[ Error ], A ] //Type of Error is immaterial

    //If I have a case class Border that takes Width and Color
    case class Border( width: SizeUnit, color: Color )
    //then what I will invoke fn2 below as such:

    
    //This function composese results.
    //Just like apply of Border would take 
    //width and color and return Border
    //this would take a Result(width), Result(color)
    //and return Result(border)
    def composeResultn2[ A, B, R ](
      resa: Result[ A ],
      resb: Result[ B ] 
      f: (A,B) => R        
    ) : Result[ R ] = {
      ( resa, resb ) match{
        case( Right( a ), Right( b ) ) => Right( f( a, b ) )
        case _ => Left( 
          Seq( a.left, b.left )
            .map( _.toOption ) 
            .flatten.flatten
        )
    }

//Invocation of composeResult2
  composeResult2( 
     Right( SizeUnit( 3 ) ), 
     Left( Error( "SomeError" ) ), 
     Border.apply 
  )