FromIBMToHALWithBreakOut

$ scala
Welcome to Scala version 2.8.0.final (Java HotSpot(TM) Client VM, Java 1.6.0_16).
Type in expressions to have them evaluated.
Type :help for more information.

scala> "IBM".map(_-1)
res0: scala.collection.immutable.IndexedSeq[Int] = Vector(72, 65, 76)

scala> "IBM".map(_-1):String
<console>:6: error: type mismatch;
 found : scala.collection.immutable.IndexedSeq[Int]
 required: String
       "IBM".map(_-1):String


scala> "IBM".map(_-1)(collection.breakOut):String
<console>:6: error: type mismatch;
 found   : java.lang.Object with scala.collection.generic.CanBuildFrom[Any,Char,String]
 required: scala.collection.generic.CanBuildFrom[String,Int,String]
       "IBM".map(_-1)(collection.breakOut):String


scala> Vector(73, 66, 77).map(_-1)(collection.breakOut):String
<console>:6: error: type mismatch;
 found   : java.lang.Object with scala.collection.generic.CanBuildFrom[Any,Char,String]
 required: scala.collection.generic.CanBuildFrom[scala.collection.immutable.Vector[Int],I\
nt,String]
       Vector(73, 66, 77).map(_-1)(collection.breakOut):String                                 ^

scala> :load Test.scala
:load Test.scala
Loading Test.scala...
defined module Test

scala> import Test._
import Test._

scala> "IBM".map(_-1):String
res2: String = HAL

scala> Vector(73, 66, 77).map(_-1)
res3: scala.collection.immutable.Vector[Int] = Vector(72, 65, 76)

scala> Vector(73, 66, 77).map(_-1)(collection.breakOut):String
res5: String = HAL

scala> 

Test.scala

object Test {
  implicit def foo = new collection.generic.CanBuildFrom[String, Int, String]{
    import collection.mutable.{Builder, StringBuilder}
    def apply(from: String) = apply()
    def apply() = new Builder[Int, String]{
      val s = new StringBuilder
      def +=(elem: Int) = { s+=(elem.toChar); this }
      def clear() = s.clear()
      def result(): String = s.result()
    }
  }
}