--- a/progs/lecture3.scala	Sun Jul 14 14:31:39 2024 +0100
+++ b/progs/lecture3.scala	Sun Sep 15 12:57:59 2024 +0100
@@ -347,6 +347,18 @@
 for (n <- 1 to 20) 
  println(fizz_buzz(n))
 
+// more interesting patterns for lists - calculate the deltas between 
+// elements
+
+def delta(xs: List[Int]) : List[Int] = xs match {
+  case Nil => Nil
+  case x::Nil => x::Nil
+  case x::y::xs => (x - y)::delta(y::xs)
+}
+
+delta(List(10, 7, 8, 2, 5, 10))
+
+
 // guards in pattern-matching
 
 def foo(xs: List[Int]) : String = xs match {
@@ -391,6 +403,16 @@
 
 fav_colour(Blue)
 
+enum ChessPiece:
+  case Queen, Rook, Bishop, Knight, Pawn
+  def value = this match
+    case Queen  => 9
+    case Rook   => 5
+    case Bishop => 3
+    case Knight => 3
+    case Pawn   => 1
+
+
 
 // ... a tiny bit more useful: Roman Numerals