diff -r efcac3016613 -r 3d585e603927 progs/app4.scala
--- a/progs/app4.scala	Mon Sep 23 17:39:31 2013 +0100
+++ b/progs/app4.scala	Mon Sep 23 22:23:55 2013 +0100
@@ -2,22 +2,21 @@
 
   val salt = "my secret key"
 
-  //SHA-1, SHA-256 + salt
+  //SHA-1 + salt
   def mk_hash(s: String) : String = {
     val hash_fun = MessageDigest.getInstance("SHA-1")
     hash_fun.digest((s + salt).getBytes).map{ "%02x".format(_) }.mkString
   }
 
-  def gt_cookie(c: Option[Cookie]) : Int = 
-    c.map(_.value.split("/")) match {
-      case Some(Array(s, h)) 
-        if (s.forall(_.isDigit) && mk_hash(s) == h) => s.toInt 
-      case _ => 0
-    }
+  def gt_cookie(c: Cookie) : Int = c.value.split("/") match {
+    case Array(s, h) 
+      if (s.forall(_.isDigit) && mk_hash(s) == h) => s.toInt 
+    case _ => 0
+  }
 
   def mk_cookie(i: Int) : Cookie = {
-    val s = i.toString
-    Cookie("visits", s + "/" + mk_hash(s))
+    val hash = mk_hash(i.toString)
+    Cookie("visits", s"$i/$hash")
   }
    
   def index = Action { request => ... }