57 lines
1.3 KiB
Prolog
57 lines
1.3 KiB
Prolog
%
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% Edinburgh IO.
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%
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see(user) :- !, set_input(user_input).
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see(F) :- var(F), !,
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'$do_error'(instantiation_error,see(F)).
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see(F) :- current_input(Stream),
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'$user_file_name'(Stream,F).
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see(F) :- current_stream(_,read,Stream), '$user_file_name'(Stream,F), !,
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set_input(Stream).
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see(Stream) :- '$stream'(Stream), current_stream(_,read,Stream), !,
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set_input(Stream).
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see(F) :- open(F,read,Stream), set_input(Stream).
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seeing(File) :- current_input(Stream),
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stream_property(Stream,file_name(NFile)),
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(
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stream_property(user_input,file_name(NFile))
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->
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File = user
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;
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NFile = File
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).
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seen :- current_input(Stream), close(Stream), set_input(user).
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tell(user) :- !, set_output(user_output).
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tell(F) :- var(F), !,
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'$do_error'(instantiation_error,tell(F)).
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tell(F) :-
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current_output(Stream),
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stream_property(Stream,file_name(F)),
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!.
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tell(F) :-
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current_stream(_,write,Stream),
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'$user_file_name'(Stream, F), !,
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set_output(Stream).
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tell(Stream) :-
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'$stream'(Stream),
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current_stream(_,write,Stream), !,
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set_output(Stream).
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tell(F) :-
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open(F,append,Stream),
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set_output(Stream).
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telling(File) :-
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current_output(Stream),
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stream_property(Stream,file_name(NFile)),
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( stream_property(user_output,file_name(NFile)) -> File = user ; File = NFile ).
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told :- current_output(Stream),
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!,
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set_output(user),
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close(Stream).
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