(VAR f x xs y )
(RULES 
        app(app(plus,0),y) -> y
        app(app(plus,app(s,x)),y) -> app(s,app(app(plus,x),y))
        app(app(times,0),y) -> 0
        app(app(times,app(s,x)),y) -> app(app(plus,app(app(times,x),y)),y)
        app(app(map,f),nil) -> nil
        app(app(map,f),app(app(cons,x),xs)) -> app(app(cons,app(f,x)),app(app(map,f),xs))
        inc -> app(map,app(plus,app(s,0)))
        double -> app(map,app(times,app(s,app(s,0))))
        
)