Input/output of DEC-10 Prolog

This section describes the built-in predicates for file manipulation inherited from DEC-10 Prolog. These predicates refer to streams by file names. The atom user is used to refer to both the standard input and standard output streams.

• see(+FileName) Makes the file FileName the current input stream. It is equivalent to:

  
  		 ( open(FileName,read,Stream),set_input(Stream)).
  

• seeing(?File) The current input stream is named FileName. It is equivalent to:

  
  		  (current_input(Stream),stream_property(Stream,file_name(FileName))).
  

• seen Closes the current input stream. It is equivalent to:

  
  		 (current_input(Stream),close(Stream)).
  

• tell(+FileName) Makes the file FileName the current output stream. It is equivalent to:

  
  		  (open(FileName,write,Stream),set_output(Stream)).
  

• telling(?FileName) The current output stream is named FileName. It is equivalent to:

  
  		   (current_output(Stream), 
  
  		   stream_property(Stream,file_name(FileName)).
  

• told Closes the current output stream. It is equivalent to:

  
  		  current_output(Stream),close(Stream).
  

• tab(N) Outputs N spaces to the current output stream.