hi, i'm pretty new to prolog and i can't get this to work :(

the predicate works fine, and appends "hay" onto an inputted word
after changing the word into an array, and then prints it to a file

change( Word, Output ) :- name(Word, Array), addv( Array, Output,
Word).

addv( [ H | T ] , Output, Word  ) :- vowel(H),
                             append( [H|T], [104, 97, 121], Array),
                             name(Output, Array),
                             tell(file) , write('lookup(') , write(Word) ,
                             write(',') , write(Output) , write(').') ,
                             nl , told.

so it writes "lookup(test, estay)." into a file

i need it to append the input to the end of the file, but it
overwrites the
whole file instead. any ideas?

thanks,
        declan

Try putting "tell" and "told" elsewhere.
Something like this :

change2( Word, Output ) :-
    tell( file ),
    write_everything( Word, Output ),
    told.

You need to define "write_everything/2".
It should not contain "tell" and "told".

You can test "write_everything/2" on its own,
before you test "change2".

Also there should be a way to append to file
instead of overwriting the file.
I think the word you need to use to do this
is called something like "file_open" or "open_file", I don't remember.
Look in the documentation for your variety of prolog.

--
Martin Sondergaard.