3 ms·

Are there any widely used statically typed languages where there is no such thing as null? Wish I could find a job using one of those!

kazinator 4y ago
Hmm, oh! C++ comes to mind. Of course, there is such a thing as null, but in: void fun(string x) // std::string { } x cannot be null. The reference semantics (like a copy of a string sharing the data with the original) is an implementation detail/optimization encapsulated inside what appears to be a value type. The tools are there in C++ to create ideal types for your problem domain which just look like value types that have no null domain value (or any other value you don't want), and standard strings are like this.
- sixstringtheory 4y ago
  You’ve moved the goal posts, but seem to have forgotten that you can create pointers to C++ strings, which then can of course be null.
  - kazinator 4y ago
    Pointers to std::string are almost never required, though. A pointer to std::string is not something you have to use to write a string handling C++ program or module; and such a pointer p is itself not a string, *p is (if p is non-null and valid). About the only time you would need a pointer to std::string when calling some C API that takes a callback function with a void * context, and you'd like that context to be a std::string. Then you might take the address of string object to pass to that API. (That pointer would likely never be null, but could go bad due to lifetime mismanagement.) Most other uses of such a thing would be unidiomatic. Whereas, in some languages, string references that can be null are foisted on programmers as the standard, idiomatic string representation. That's a big difference.
kaashif 4y ago
No such thing as null? No. But in Kotlin non-nullable types are the default. In C++ references are non-nullable. Both include nullable types too. In that specific example, String can't be null in Kotlin and neither can string in C++, although you can make them nullable by using e.g. a pointer or an optional type. Having everything be nullable like in Java is unarguably 100% a mistake.

kazinator 4y ago

Hmm, oh! C++ comes to mind. Of course, there is such a thing as null, but in: void fun(string x) // std::string { } x cannot be null. The reference semantics (like a copy of a string sharing the data with the original) is an implementation detail/optimization encapsulated inside what appears to be a value type. The tools are there in C++ to create ideal types for your problem domain which just look like value types that have no null domain value (or any other value you don't want), and standard strings are like this.

sixstringtheory 4y ago
You’ve moved the goal posts, but seem to have forgotten that you can create pointers to C++ strings, which then can of course be null.
- kazinator 4y ago
  Pointers to std::string are almost never required, though. A pointer to std::string is not something you have to use to write a string handling C++ program or module; and such a pointer p is itself not a string, *p is (if p is non-null and valid). About the only time you would need a pointer to std::string when calling some C API that takes a callback function with a void * context, and you'd like that context to be a std::string. Then you might take the address of string object to pass to that API. (That pointer would likely never be null, but could go bad due to lifetime mismanagement.) Most other uses of such a thing would be unidiomatic. Whereas, in some languages, string references that can be null are foisted on programmers as the standard, idiomatic string representation. That's a big difference.

kaashif 4y ago

No such thing as null? No. But in Kotlin non-nullable types are the default. In C++ references are non-nullable. Both include nullable types too. In that specific example, String can't be null in Kotlin and neither can string in C++, although you can make them nullable by using e.g. a pointer or an optional type. Having everything be nullable like in Java is unarguably 100% a mistake.