Scala : sandbox Scala : add 8-pattern-matching

1 files changed, 29 insertions, 0 deletions

diff --git a/Scala/sandbox/8-pattern-matching.scala b/Scala/sandbox/8-pattern-matching.scala
new file mode 100644
index 0000000..36beb68
--- /dev/null
+++ b/Scala/sandbox/8-pattern-matching.scala
@@ -0,0 +1,29 @@
+object PatternMatching
+{
+  trait Expr {
+    def eval: Int = this match {
+      case Number(n) => n
+      case Sum(e1, e2) => e1.eval + e2.eval
+    }
+    def show: String = this match {
+      case Number(n) => n.toString
+      case Sum(e1, e2) => e1.show + " + " + e2.show
+    }
+  }
+
+  case class Number(n: Int) extends Expr
+  case class Sum(e1: Expr, e2: Expr) extends Expr
+
+
+  def eval1(e: Expr): Int = e match {
+    case Number(n) => n
+    case Sum(e1, e2) => eval1(e1) + eval1(e2)
+  }
+
+  def run = {
+    println("PatternMatching")
+    println( eval1(Sum(Number(1), Number(2))) )
+    val e = Sum(Number(1), Number(2))
+    println( e.show + " = " + e.eval )
+  }
+}