Recursive Prolog predicate for reverse / palindrome

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Ad 1: It is impossible to define reverse/2 as a (directly edit thx to @repeat: tail) recursive predicate – unless you permit an auxiliary predicate.

Ad 2:

palindrome(X) :- reverse(X,X).

But the easiest way is to define such predicates with DCGs:

iseq([]) --> [].
iseq([E|Es]) --> iseq(Es), [E].

reverse(Xs, Ys) :-
   phrase(iseq(Xs), Ys).

palindrome(Xs) :-
   phrase(palindrome, Xs).

palindrome --> [].
palindrome --> [E].
palindrome --> [E], palindrome, [E].

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