Problem Statement

Create a program that, when run, would display all integers from   1   to   ∞   (or any relevant implementation limit),   in sequence   (i.e.   1, 2, 3, 4, etc)   if given enough time.

An example may not be able to reach arbitrarily-large numbers based on implementations limits.   For example, if integers are represented as a 32-bit unsigned value with 0 as the smallest representable value, the largest representable value would be 4,294,967,295.   Some languages support arbitrarily-large numbers as a built-in feature, while others make use of a module or library. If appropriate, provide an example which reflect the language implementation's common built-in limits as well as an example which supports arbitrarily large numbers, and describe the nature of such limitations—or lack thereof.

Let's start with the solution:

program Intseq
  implicit none
  
  integer, parameter :: i64 = selected_int_kind(18)
  integer(i64) :: n = 1
  
! n is declared as a 64 bit signed integer so the program will display up to
! 9223372036854775807 before overflowing to -9223372036854775808  
  do
    print*, n
    n = n + 1
  end do
end program