(VAR fun x xs y )
(RULES 
        app(f, app(s, x)) -> app(f, x)
        app(g, app(app(cons, 0), y)) -> app(g, y)
        app(g, app(app(cons, app(s, x)), y)) -> app(s, x)
        app(h, app(app(cons, x), y)) -> app(h, app(g, app(app(cons, x), y)))
        app(app(map, fun), nil) -> nil
        app(app(map, fun), app(app(cons, x), xs)) -> app(app(cons, app(fun, x)), app(app(map, fun), xs))
        app(app(filter, fun), nil) -> nil
        app(app(filter, fun), app(app(cons, x), xs)) -> app(app(app(app(filter2, app(fun, x)), fun), x), xs)
        app(app(app(app(filter2, true), fun), x), xs) -> app(app(cons, x), app(app(filter, fun), xs))
        app(app(app(app(filter2, false), fun), x), xs) -> app(app(filter, fun), xs)
        
)