They have, in the past, reached for LISP and various other languages. What matters for life-critical systems isn't the presence or absence of a formal specifica

They have, in the past, reached for LISP and various other languages. What matters for life-critical systems isn't the presence or absence of a formal specification. It's more important to foster a culture of design verification and validation of tooling. You can use Brainfuck in a medical device provided you can create the right organizational architecture to ensure the quality of your Brainfuck code. It's more about creating a rational engineering organization and having a process of searching for problems and solving them proactively rather than waiting for your customers to test your code. Of course most rational engineering organizations wouldn't choose Brainfuck because it's harder to write code that other people can evaluate. But it's not automatically out of the question if you have a good reason for its use.