Scala 2.8 breakOut

Question

In Scala 2.8, there is an object in scala.collection.package.scala:

def breakOut[From, T, To](implicit b : CanBuildFrom[Nothing         


        

Answer 1

A simple example to understand what breakOut does:

scala> import collection.breakOut
import collection.breakOut

scala> val set = Set(1, 2, 3, 4)
set: scala.collection.immutable.Set[Int] = Set(1, 2, 3, 4)

scala> set.map(_ % 2)
res0: scala.collection.immutable.Set[Int] = Set(1, 0)

scala> val seq:Seq[Int] = set.map(_ % 2)(breakOut)
seq: Seq[Int] = Vector(1, 0, 1, 0) // map created a Seq[Int] instead of the default Set[Int]