+printEval :: (A.v: v a | expr v) -> (Maybe a, String)
+//printEval f = (f, let (Print p) = f in p)
+printEval f = (eval f, print f)
+
+//Mag niet
+//Start :: (Maybe Int, String)
+//Start = printEval (lit 4 + lit 38)
+
+//Mag wel
+Start = let (Print f) = lit 4 + lit 38 in f