%query: palindrome(i). %% palindrome(Xs) :- the list Xs equals to its reverse. %% %TWTYPES :- type palindrome(list). palindrome(Xs) :- reverse(Xs, Xs). %TWTYPES :- type reverse(list,list). reverse(X1s, X2s) :- reverse(X1s, [], X2s). %TWTYPES :- type reverse(list,list,list). reverse([], Xs, Xs). reverse([X | X1s], X2s, Ys) :- reverse(X1s, [X | X2s], Ys). /*TWDESC palindrome(Xs) :- the list Xs equals to its reverse. */ /*TWTYPES list([]). list([X|Xs]) :- poly(X), list(Xs). poly(dummy). */ /*TWDEMO selected_norms([list,poly]). query(palindrome(b,f)). query(palindrome(f,b)). query(reverse(b,f,f,f,f,f)). query(reverse(f,b,f,f,f,f)). query(reverse(b,f,f,f)). query(reverse(f,b,f,f)). */
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