Fortran, function overloading on arity

example.f90

program example
  use naryfunc
  implicit none
  ! Outputs 2 6 24
  write(*,*) mult(2), mult(2, 3), mult(2, 3, 4)
end program example

naryfunc.f90

module naryfunc
  implicit none

  private
  public mult

  interface mult
    module procedure mult1, mult2, mult3
  end interface

contains

  pure function mult1(x)
    integer, intent(in) :: x
    integer :: mult1

    mult1 = x
  end function mult1

  pure function mult2(x, y)
    integer, intent(in) :: x, y
    integer :: mult2

    mult2 = x * y
  end function mult2

  pure function mult3(x, y, z)
    integer, intent(in) :: x, y, z
    integer :: mult3

    mult3 = x * y * z
  end function mult3

end module naryfunc