List to Map in Scala

listToMap.scala

scala> :paste
// Entering paste mode (ctrl-D to finish)

def listToMap[T](list: List[T])(init : Map[T,T] = Map[T,T]()): Map[T,T] = list match {
   case Nil       => init
   case a :: Nil => init
   case a :: b :: rest =>  listToMap(rest)( init + (a -> b))
}

// Exiting paste mode, now interpreting.

listToMap: [T](list: List[T])(init: Map[T,T])Map[T,T]

scala> listToMap(List(1,2,3,4))
<console>:12: error: missing arguments for method listToMap;
follow this method with `_' if you want to treat it as a partially applied function
       listToMap(List(1,2,3,4))
                ^

scala> listToMap(List(1,2,3,4))()
res1: Map[Int,Int] = Map(1 -> 2, 3 -> 4)

scala> listToMap(List(1,2,3,4,5))()
res2: Map[Int,Int] = Map(1 -> 2, 3 -> 4)

scala> listToMap(List(1,2,3,4,5,6))()
res3: Map[Int,Int] = Map(1 -> 2, 3 -> 4, 5 -> 6)