let echo chan = 
  try while true do print_string (input_line chan); print_newline() done
  with End_of_file -> ();;

if Array.length Sys.argv <= 1 then echo stdin
else
  for i = 1 to Array.length Sys.argv - 1 
  do
    let chan = open_in Sys.argv.(i) in
    echo chan;
    close_in chan
  done;;