Let us take our input data from a file called ``in''.
go:-see(in)
test
seen.
We wrap the test/0 predicate into a predicate go/0 which takes input from the specified file ``in''. This file should contain legal Prolog terms ---for the predicate double/2 we want something like:
2.23.
-1.
Now to redirect output to a file named ``out'':
go:-Using the same file ``in'' as previously ``out'' will contain:tell(out)
see(in)
test
seen
told.
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