% Source: http://www.cs.bgu.ac.il/cgi-bin/genaim/TerminWeb/term_check?example=rotate

rotate(X,Y) :- append(A,B,X), append(B,A,Y).

append([X|Xs],Ys,[X|Zs]) :- append(Xs,Ys,Zs).
append([],Ys,Ys).