Section FoldRightComp.
Variables (T1 T2 : Type) (h : T1 -> T2).
Variables (R : Type) (f : T2 -> R -> R) (z0 : R).

Lemma foldr_cat s1 s2 : foldr f z0 (s1 ++ s2) = foldr f (foldr f z0 s2) s1.