[the_why_of_y]

Concurrency safety and memory safety can definitely be circumvented in D and SBCL too.

https://dlang.org/spec/memory-safe-d.html

https://dlang.org/blog/2016/09/28/how-to-write-trusted-code-...

http://sbcl.org/manual/index.html#Declarations-as-Assertions