Logical streams may be matched to their physical stream numbers by using get_stream/2.
Stream can be any existing stream number or symbolic stream name as long as it has a mode compatible with that of StreamId.
StreamId can be a user-defined symbolic stream name, or else one of the system systems: input , output , error, user, toplevel_input, toplevel_output, answer_output, debug_input, debug_output.
A user-defined symbolic stream is not automatically updated when the stream to which it points is changed or closed.
Success: [eclipse]: open(file1,update,s), set_stream(output,s), > writeln(output,hi), flush(output). yes. [eclipse]: seek(s,0), read(s,X). X = hi yes. Error: set_stream(a, S). (Error 4). set_stream(1.0, S). (Error 5). set_stream(a, nonex). (Error 193).