An Integer Function Return Value
     Prolog:  [-integer]
     C:       long int f(...)
                  long int x;
                  return x;
     Pascal:  function f(...): integer;
                var x: integer;
                  f := x;
     FORTRAN: integer function f(...)
                integer x
                f = x

No argument is passed to the foreign function. The return value from the function is assumed to be a long integer. It is converted to a Prolog integer and unified with the corresponding argument of the Prolog call. The argument can be of any type; if it cannot be unified with the returned integer, the call fails.