Initial data commit

Task/Stack/Scala/stack-1.scala

@@ -0,0 +1,17 @@
+class Stack[T] {
+  private var items = List[T]()
+
+  def isEmpty = items.isEmpty
+
+  def peek = items match {
+    case List()       => error("Stack empty")
+    case head :: rest => head
+  }
+
+  def pop = items match {
+    case List()       => error("Stack empty")
+    case head :: rest => items = rest; head
+  }
+
+  def push(value: T) = items = value +: items
+}