%query: len(i,o). %% len(Xs, X) :- X is the length of the list Xs. %% %TWTYPES :- type len(list,nat). len([], 0). len([_ | Ts], s(N)) :- len(Ts, N). /*TWDESC len(Xs, X) :- X is the length of the list Xs. */ /*TWTYPES list([]). list([X|Xs]) :- poly(X), list(Xs). poly(dummy). nat(0). nat(s(X)) :- nat(X). */ /*TWDEMO selected_norms([list,nat,poly]). query(len(b,f,f,f,f,f)). query(len(f,f,b,f,f,f)). query(len(f,f,f,f,b,f)). */
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