Nested functions in Fortran (2003, 2008…)

counter2.f03

module counter2
  implicit none
  
  type element
     character(len=16) :: s
     integer :: e1, e2
  end type element
  
contains
  function count_unique(s) result(c)
    implicit none
    integer :: c
    type(element), dimension(:), intent(in) :: s


    integer :: i, j
    logical :: found

    c = 0
    do i = 1, size(s)
       found = .false.
       do j = 1, i-1
          if (comp(i, j) == 0) then
             found = .true.
             exit
          end if
       end do
       if (.not. found) c = c + 1
    end do
    
  contains
    
    function comp(i, j) result(d)
      implicit none
      integer :: d
      integer, intent(in) :: i, j

      if (s(i)%e2 == s(j)%e2) then
         d = 0
      else if (s(i)%e1 /= s(j)%e1) then
         d = s(j)%e1 - s(i)%e1
      else
         d = s(j)%e2 - s(i)%e2
      end if
    end function comp
  end function count_unique

end module counter2

local2.f03

program local2
  use counter2
  implicit none

  integer :: i

  type(element), dimension(4) :: s = [ &
       element("zak", 2, 0), &
       element("mac", 3, 1), &
       element("abc", 4, 2), &
       element("zak", 5, 0) ]
  
  print *, count_unique(s)

  do i = 1, size(s)
     print *, "<" // trim(s(i)%s) // ">"
  end do

end program local2

Thanks for the example!