I agree with your frustrations but I don't think the blame is on "let it crash". As far as helping prevent bugs, let it crash won't help. It is not a replaceme

I agree with your frustrations but I don't think the blame is on "let it crash". As far as helping prevent bugs, let it crash won't help. It is not a replacement for a type system either. A type system for Elixir would definitely help you prevent bugs (but unfortunately implementing one is challenging). Let it crash is a mental model and a technique to handle bugs and avoid undefined behaviour when all other attempts to prevent them (be it via static types, testing, code reviews, etc) failed. Imagine some data validation functionality had a flaw and that causes bad data to reach a core component, would you rather: 1. have the core component continue functioning with said bad input, which may have unknown repercussions? 2. have the core component crash and restart itself with a known state? So let it crash can be useful to guarantee your system is not going to venture into undefined behaviour. I wrote a small example of this in a blog post about assertive code (http://blog.plataformatec.com.br/2014/09/writing-assertive-code-with-elixir/ http://blog.plataformatec.com.br/2014/09/writing-assertive-c...). If you compare the two get_token implementations, you are 100% correct that in the second implementation, if you receive bad input, the code will crash over and over again. But I would say that I prefer the crash, so I can think about how I want to handle said input, rather than have an implementation that works by accident (and the accident may be a happy or an unhappy one). Would I prefer to have foreseen the bad input in the first case? Of course! And do type systems help avoid undefined behaviour? Definitely! But not all of them. It would be great if we could have both. On a larger scale, especially when building complex systems, you are going to interface with client/server, database, apis, etc and you will run into unexpected scenarios. You likely can't prevent, model, or foresee all of them, so "let it crash" works as a default behaviour to handle them. It is also a legit strategy for things you know that may happen, but the best way to handle them is to start over anyway. It provides a mental model for you to reason when things go wrong at each individual component, instead of trying to reason how an exception may affect the whole system. I am not sure if this helps, so questions and feedback is appreciated!