I am not sure which pillar of functional programming is lost with labelled arguments? Partial applications still work, higher-order function too. One might need

I am not sure which pillar of functional programming is lost with labelled arguments? Partial applications still work, higher-order function too. One might need to use anonymous functions when labels does not match but I don't see any pillar being lost. In the same way, it is perfectly possible to switch to the imperative style only in the specific code path where performance really matters and use abstraction to isolate this performance-sensitive part from the rest of your application. Ideally, you can then keep both the elegance of functional programming and the performance of imperative programming.