with Ada.Text_IO; use Ada.Text_IO;
procedure Main is
   task My_Task;
   task body My_Task is
   begin
      for I in 1 .. 4 loop
         Put_Line ("Hello from My_Task");
      end loop;
   end;
begin
   for I in 1 .. 4 loop
      Put_Line ("Hello from Main");
   end loop;
end;
The order of Put_Line can vary.
Hello from My_Task
Hello from My_Task
Hello from Main
Hello from My_Task
Hello from Main
Hello from My_Task
Hello from Main
Hello from Main