[Certhas]

In Julia you have positional and keyword arguments, separated by a semicolon.

  function f(; a, b)
    a+b
  end

Default values are optional. This can only be called with named arguments like f(; a=5, b=7). Unfortunately the separation isn't required to be explicit when calling the function, so calling f(a=5, b=7) also works. Generally calling functions is extremely permissive (e.g. a function with two positional and two keyword arguments function g(a, b=5; c, d=8) can be called with keywords and positions interleaved g(1, c = 7, 5)), leading to potential confusion at the call site. Our coding guidelines enforce separation of positional and keyword at call sites, and with that additional restriction I have found Julias behaviour in this regard very pleasant. E.g.:

  calc_something(a, b; bool_flag=true)

is the best style for this type of thing that I have seen.