[eterps]

> But I am using Oberon-07 as base, and I might deviate from it quite soon too.

I am curious about your thoughts on var parameters (i.e. mutable references), as in:

    proc increment(var x: int)
    begin
      x := x + 1
    end

    var i: int

    begin
      i := 10
      increment(i)  // i is now 11
    end

[gnatmud8]

i also wonder about this concept; is there a programming language that has this behavior?

[eterps]

Ada, Nim, Pascal. I think C++ also offers it with a specific syntax.

Rust also offers it, but you need to specify it on the call side as well.

[v9v]

Fortran can do "in out" arguments to subroutines also.