(VAR f x xs )
(RULES 
        app(app(mapt,f),app(leaf,x)) -> app(leaf,app(f,x))
        app(app(mapt,f),app(node,xs)) -> app(node,app(app(maptlist,f),xs))
        app(app(maptlist,f),nil) -> nil
        app(app(maptlist,f),app(app(cons,x),xs)) -> app(app(cons,app(app(mapt,f),x)),app(app(maptlist,f),xs))
        
)