As a mathematician I like the positional notation, but once we assign meaning to the slots it gets weird, so I had the same objection. One could add some new n

As a mathematician I like the positional notation, but once we assign meaning to the slots it gets weird, so I had the same objection. One could add some new notation to distinguish the element _T_ from the slot _T_. For example let’s write slots as _[T]_ (I’m not creative enough to come up with something good), then we can talk about ∂_[T]F or ∂F/∂[T]. One can think of the [.] operator as mapping from “semantic symbol” to slot number in a way.