add examples

examples/sumList.hs

@@ -0,0 +1,9 @@
+nil = Pack{0 0};
+cons x y = Pack{1 2} x y;
+list = cons 1 (cons 2 (cons 3 nil));
+sum l = case l of
+    { 0      -> 0
+    ; 1 x xs -> (+#) x (sum xs)
+    };
+main = sum list;
+