MiniKanren twinso
(define twinso
(lambda (s)
(fresh (x y)
(conso x y s) ;; s is a list of 2 elements, x `cons` (y)
(conso x () y)))) ;; these elements should be the same
Without conso
(define twinso
(lambda (s)
(fresh (x)
(== '(x x) s))))