Scala : add 5-intlist.scala

2 files changed, 36 insertions, 0 deletions

diff --git a/Scala/sandbox/0-main.scala b/Scala/sandbox/0-main.scala
index 3596e33..2092d9d 100644
--- a/Scala/sandbox/0-main.scala
+++ b/Scala/sandbox/0-main.scala
@@ -7,5 +7,6 @@ object Main  extends App {
     Curry.run
     Rationals.run
     IntSet.run
+    IntList.run
 
 }
diff --git a/Scala/sandbox/5-intlist.scala b/Scala/sandbox/5-intlist.scala
new file mode 100644
index 0000000..6b29401
--- /dev/null
+++ b/Scala/sandbox/5-intlist.scala
@@ -0,0 +1,35 @@
+
+object IntList {
+
+  trait List [T] {
+    def isEmpty: Boolean
+    def head: T
+    def tail: List[T]
+    def nth(n: Int): T
+  }
+
+  class Cons[T](val head: T, val tail: List[T]) extends List[T] {
+    def isEmpty = false
+    def nth(n: Int): T = {
+      if (isEmpty) throw new IndexOutOfBoundsException
+      if (n==0) head
+      else tail nth(n - 1)
+    }
+  }
+
+  class Nil[T] extends List[T] {
+    def isEmpty: Boolean = true
+    def head: Nothing = throw new NoSuchElementException("Nil.head")
+    def tail: Nothing = throw new NoSuchElementException("Nil.tail")
+    def nth(n: Int): Nothing = throw new NoSuchElementException("Nil.nth")
+  }
+
+
+  def run = {
+    println("IntList")
+    val list = new Cons(1, new Cons(2, new Cons(3, new Nil)))
+    println(list nth 2)
+    println(list nth 0)
+    /* println(list nth 5) */
+  }
+}