Well, if it is truly unexpected that it doesn't match the data, then you should just blow the process up and have it be automatically restarted by a supervisor.

Well, if it is truly unexpected that it doesn't match the data, then you should just blow the process up and have it be automatically restarted by a supervisor. If the pattern is an alternative format, or something that you'll actually want to match, you just define another function with that pattern to test it against.