--- a/progs/app4.scala	Sun Sep 21 17:40:04 2014 +0100
+++ b/progs/app4.scala	Sun Sep 21 23:23:43 2014 +0100
@@ -1,15 +1,17 @@
-val http_pattern = """\"https?://[^\"]*\"""".r
+val http_pattern = """"https?://[^"]*"""".r
 val my_urls = """urbanc""".r
 val email_pattern = 
   """([a-z0-9_\.-]+)@([\da-z\.-]+)\.([a-z\.]{2,6})""".r
 
+def print_str(s: String) = 
+  if (s == "") () else println(s)
+
 def crawl(url: String, n: Int) : Unit = {
   if (n == 0) ()
   else {
     println(s"Visiting: $n $url")
     val page = get_page(url)
-    println(email_pattern.findAllIn(page).mkString("\n"))
-    for (u <- get_all_URLs(page)) 
-      crawl(u, n - 1)
+    print_str(email_pattern.findAllIn(page).mkString("\n"))
+    for (u <- get_all_URLs(page).par) crawl(u, n - 1)
   }
 }