⇨ Joe Armstrong On Defensive Programming

Note this method of structuring cannot be done in a sequential language - since there is only one thread of control - thus in a sequential language all error handling MUST be done within the process itself.
That's why you have to program defensively in a sequential language - you get one thread of control and one chance to fix your error.

— Joe Armstrong

I can not warm up to Erlang language and syntax but there is no denying that the Erlang worker/observer model is much more simpler and simple to figure out that code which mixes business logic and error handling.

(via @debasishg)