
current_stream(?Stream)

   Succeeds if Stream is a currently open stream. 

Arguments
   Stream              Variable, stream handle, or atom.

Type
   Stream I/O

Description

   Used to test whether a given identifier or handle denotes an open stream,
   or enumerates all currently open streams on backtracking.

   When called with a variable argument, only stream handles are returned,
   not any symbolic aliases.



Modes and Determinism
   current_stream(+) is semidet
   current_stream(-) is nondet

Fail Conditions
   Fails if Stream is instantiated but does not denote an open stream.

Exceptions
     5 --- Stream is instantiated, but not to an atom or stream handle.

Examples
   
Success:
    ?- current_stream(S), writeln(S), fail.
    $&(stream,0)
    $&(stream,1)
    $&(stream,2)
    $&(stream,3)
    $&(stream,4)
    $&(stream,5)
    $&(stream,6)
    $&(stream,8)
    No (0.00s cpu)

    ?- current_stream(output).
    Yes (0.00s cpu)

    ?- current_stream(junk).
    No (0.00s cpu)


See Also
   open / 3, open / 4, get_stream_info / 3, get_stream / 2
