src/Pure/System/isabelle_system.scala

   def admin(): Boolean = Path.explode("~~/Admin").is_dir
 
 
   /* default logic */
 
-  def default_logic(args: String*): String = {
-    args.find(_ != "") match {
-      case Some(logic) => logic
-      case None => getenv_strict("ISABELLE_LOGIC")
-    }
-  }
+  def default_logic(args: String*): String =
+    args.find(_.nonEmpty) getOrElse getenv_strict("ISABELLE_LOGIC")
 
 
   /* download file */
 
   def download(url_name: String, progress: Progress = new Progress): HTTP.Content = {