%query: len1(i,o). %% len1(Xs, X) :- X is the length of the list Xs. %% %TWTYPES :- type len1(list,nat). len1([], 0). len1([_ | Ts], N) :- len1(Ts, M), eq(N,s(M)). %TWTYPES :- type eq(nat,nat). eq(X,X). /*TWDESC len1(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(len1(b,f,f,f,f,f)). query(len1(f,f,b,f,f,f)). */
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