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Comment by everybodyknows | Hacker News Reader

null safety: Can you provide us a reference to a working definition of the term?

For example in Typescript, you can specify whether a parameter is allowed to be null in the signature of a function. If you do the compiler will make sure that you don't accidentally pass a null value to that function.

  function foo(x: number) {
    return x + 1;
  }

  let y = null;
  foo(y); // compiler will flag this

In Go

    func foo(x int) { return x + 1 }
    var y *int = nil
    foo(y) // compiler will flag thi

Now add an error to foo and have x=0 as a valid return value, or even worse, having to deal differently with different errors.

That wasn't the greatest example as Go doesn't really have any way to represent it. If it did it might be something like this.

  type MyStruct struct {
    Name string
  }

  var-not-nil myStruct = &MyStruct{"Hello"} // this is a "not-nil" pointer variable

  myStruct = nil // compiler would catch this

The idea being to allow variables to hold and pass pointers to structs like now but ensure they are never nil.

null/nil can only occur in scoped use cases (Option<Foo>, Foo | null, Foo?) and so the compiler can warn you when something could be missing and you don't handle it without being incredibly noisy.

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