Shen Prolog

(0-) (defprolog member
   X [X | _] <--;
   X [_ | Y] <-- (member X Y);)
(fn member)

(1-) (defprolog rev
       [] [] <--;
       [X | Y] Z <-- (rev Y W) (conc W [X] Z);)
(fn rev)

(2-) (defprolog conc
  [] X X <--;
  [X | Y] Z [X | W] <-- (conc Y Z W);)
(fn conc)

(3-) (prolog? (member 1 [1 2]))
true

(4-) (prolog? (member 0 [1 2]))
false

(5-) (prolog? (member X [1 2]))
true

(6-) (prolog? (member X [1 2]) (return X))
1

(7-) (prolog? (rev [1 2] X) (return X))
[2 1]