> I don't see how making types non-nullable solves the problem, doesn't it just create a new problem? When I load the string from somewhere outside of the program, if it is not present, I would either have to check for that condition otherwise I will crash
If the type is non-nullable then the compiler will refuse the program if you have not dotted your is and crossed your ts. So you'd have to check your expectations at the edge, and if the expectation is "that is indeed optional" then it's optional internally and the compiler will ensure that is acknowledged at every place it's used.
> otoh, if the strings are not external then there is little danger of things ever being null no?
It depends. Lots of things are internally nullable. If I look an account by a key that's been provided externally, the account may or may not exist, that's an optional.
However it's true that most of the internal values will be non-nullable, and then the advantage of non-nullable types is that is checked and validated by the compiler, so it avoids misuses and misunderstandings.
When you only have nullable types, then the only thing you can do is assume, everywhere, and pray that you're right.
If the type is non-nullable then the compiler will refuse the program if you have not dotted your is and crossed your ts. So you'd have to check your expectations at the edge, and if the expectation is "that is indeed optional" then it's optional internally and the compiler will ensure that is acknowledged at every place it's used.
> otoh, if the strings are not external then there is little danger of things ever being null no?
It depends. Lots of things are internally nullable. If I look an account by a key that's been provided externally, the account may or may not exist, that's an optional.
However it's true that most of the internal values will be non-nullable, and then the advantage of non-nullable types is that is checked and validated by the compiler, so it avoids misuses and misunderstandings.
When you only have nullable types, then the only thing you can do is assume, everywhere, and pray that you're right.