Closing a Stream

• close(X) closes the stream corresponding to X.

  If X is a stream object, then if the corresponding stream is open, it will be closed; otherwise, close/1 succeeds immediately, taking no action.

  If X is a file specification, the corresponding stream will be closed. It is only closed if the file was opened by see/1 or tell/1. In the example

            see(foo),
            ...
            close(foo)
            

  foo will be closed. However, in the example

            open(foo, read, S),
            ...
            close(foo)
            

  an exception will be raised and foo will not be closed.

• told/0 closes the current output stream. The current output stream is then set to be user_output; that is, the user's terminal.
• seen/0 closes the current input stream. The current input stream is then set to be user_input; that is, the user's terminal.