Make Monad abstract again

ircmaxell · ircmaxell · commit 64807c92cd82 · 2013-07-05T08:40:24.000-04:00
diff --git a/lib/MonadPHP/Monad.php b/lib/MonadPHP/Monad.php
@@ -2,7 +2,7 @@
 
 namespace MonadPHP;
 
-class Monad {
+abstract class Monad {
 
     protected $value;
 
