The syntax <expr> <pipe> <lambda> is unambiguous and consistent with existing semantics, so we could add it as a convenience over <expr> <pipe> (<lambda>), though we'd have to ensure that

a |> x -> x |> f

was parsed as

a |> x -> (x |> f)

and not as

a |> (x -> x) |> f

to be consistent with current precedence ordering.