sig funs. % import list. type mapfun (A -> B) -> list A -> list B -> o. type foldr (A -> B -> B) -> B -> list A -> B -> o. type foldl (A -> B -> A) -> A -> list B -> A -> o.
sig funs. % import list. type mapfun (A -> B) -> list A -> list B -> o. type foldr (A -> B -> B) -> B -> list A -> B -> o. type foldl (A -> B -> A) -> A -> list B -> A -> o.