> A caveat to #2 is that depending on the language, it may be possible to override safety, for example Haskell's fromJust can throw an exception if used on a missing value. But this tends to require conscious effort, and can easily be checked for automatically, since it involves the use of unsafe function calls.
A much scarier example there is C++, where std::optional can be deref'd (literally `*opt`, the easiest and shortest thing you can do with it)… and just UBs on an empty optional. Because C++ hates both type-safety and memory-safety.
This achieves two things:
1. It allows you to define functions that cannot return NULL, and the compiler guarantees this. This is a huge win - you no longer have NULL as a possible return value for many functions.
2. Values belonging to the option type have to be unwrapped to access their contents, so it's not possible to unknowingly dereference a missing value. This is an even bigger win than #1, because it can literally eliminate null pointer errors.
A caveat to #2 is that depending on the language, it may be possible to override safety, for example Haskell's fromJust can throw an exception if used on a missing value. But this tends to require conscious effort, and can easily be checked for automatically, since it involves the use of unsafe function calls.