Nim solves this problem by only having two explicit, restricted nullable types: Pointers and references. Pointers are manually managed, references are automatic

Nim solves this problem by only having two explicit, restricted nullable types: Pointers and references. Pointers are manually managed, references are automatically managed, both start as nil and must have their referenced objects instantiated manually. The entire rest of the language is built on pass-by-value using stack values and stack-managed hidden unique pointers. You basically never actually need to use a ref or a pointer unless you're building an interface to a C or C++ library. I having written a 40k line production application with no reference or pointer types anywhere. Almost any case you'd need is covered by simply passing a compound type or dynamic container as a mutable value, where it's impossible to perform any kind of pointer or reference semantics on it. The lifetime is already managed, so semantically it's just a value.