C# allows file-level namespaces so you can write

    namespace Math;

    static class Adder {
      public static int Add(...) { ... }
    }

(one nesting level less). Next, elsewhere you can write

    namespace Whatever;
    using static Math.Adder;

    class CC {
      void M() {
        var z = Add(10, 20); // no NS qualification needed due to using static above
      }
    }

Java enforces directory structure to reflect package names, and this feature is not universally popular.

I agree with the first example. I wish C# could do “free” floating functions which just lives in the namespace itself. Your second example could do with the extra namespace indentation by doing

namespace math;

But why?

Having to use class/struct instead of free floating funcs tries to force some hierarchy, architecture, etc

Which eventually makes the code better *globally*

I was arguing that the hierarchy is already in your path. The explicit namespace (and even the class name) is redundant if what you want are mostly functions.

Currently, you're forced to define the hierarchy in the directory structure, and then again with namespaces. There should be a way to opt out of this.

Ok, I see

As of now you can opt out of physical hierarchy (file patches)

I think logical hierarchy is better because you avoid stupid things like moving file to other folder causing compilation errors.

I've witnessed too much of such issues in C++/cmake world to want it.