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package examples
object patterns {
trait Tree
case class Branch(left: Tree, right: Tree) extends Tree
case class Leaf(x: Int) extends Tree
val tree1 = Branch(Branch(Leaf(1), Leaf(2)), Branch(Leaf(3), Leaf(4)))
def sumLeaves(t: Tree): Int = t match {
case Branch(l, r) => sumLeaves(l) + sumLeaves(r)
case Leaf(x) => x
}
def find[a,b](it: Iterator[Pair[a, b]], x: a): Option[b] = {
var result: Option[b] = None
var found = false
while (it.hasNext && !found) {
val Pair(x1, y) = it.next
if (x == x1) { found = true; result = Some(y) }
}
result
}
def printFinds[a](xs: List[Pair[a, String]], x: a) =
find(xs.iterator, x) match {
case Some(y) => System.out.println(y)
case None => System.out.println("no match")
}
def main(args: Array[String]) {
println("sum of leafs=" + sumLeaves(tree1))
printFinds(List(Pair(3, "three"), Pair(4, "four")), 4)
}
}
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