PLOGHELP TELL                               Robert Duncan, February 1988


    ?- tell(Stream).


Changes the current output stream to be Stream. Stream must be
instantiated to one of:

    - an atom representing a file name, such as

        '~/prolog/dbase.pl'

    - either of the two special output stream names: 'user' (which
      refers to the user's terminal) or 'errchan' (which refers to an
      output stream reserved for error and debugging messages, usually
      the terminal also);

    - a POP-11 character consumer.

After invoking tell/1 on a stream, any subsequent output (whether
produced by write/1, put/1, listing/1 or similar) will be sent to the
named stream until either it is closed by a call to told/0 or a new
stream is selected with another "tell". For example, the goal:

    ?- tell('~/prolog/dbase.pl'), listing.

will write all current predicate definitions which have clauses to the
file '~/prolog/dbase.pl'.

The general behaviour of streams is described in PLOGHELP * I_O.


-- RELATED DOCUMENTATION ----------------------------------------------

PLOGHELP * I_O
    Overview of input/output operations in Prolog.

PLOGHELP * SEE, * SEEING, * SEEN
    Operations on input streams.

PLOGHELP * TELLING
    Determines the name of the current output stream.

PLOGHELP * TOLD
    Closes the current output stream.

--- C.all/plog/help/tell -----------------------------------------------
--- Copyright University of Sussex 1988. All rights reserved. ----------