(VAR a k x y)

(DATATYPES
   a = µX. < empty, cons(b,X) >
   b = < >
 )

(SIGNATURES f :: a x a -> a
 )


(RULES
   f(x,empty) -> x
   f(empty,cons(a,k)) -> f(cons(a,k),k)
   f(cons(a,k),y) -> f(y,k)
)