add illustration samples

samples/fpsamples/sample1.erl

@@ -0,0 +1,14 @@
+% Message passing in Erlang - the "add" and "mult"
+% identifiers are "atoms", constant values that are
+% used to match incoming messages (which are technically
+% tuples).
+
+loop() ->
+    receive
+        {add, A, B} -> 
+            io:format("adding: ~p~n", [A + B]),
+            loop();
+        {mult, A, B} -> 
+            io:format("multiplying: ~p~n", [A * B]),
+            loop()
+    end.