[delayed]

Yes Gleam allows you to do f(arg, _)

See the relevant docs: https://tour.gleam.run/everything/#functions-function-captur...

But that's a single argument right?

Seems more limiting than the closure way. Scala allows multiple _ but in turn that doesn't allow changing ordering.

TBH, I feel this stuff is not really worth it,

I think the single hole version is a good compromise compared to actual currying or multiple holes, since it's strictly better than something like first or last argument threading (e.g. ->, ->> in Clojure), easier to reason about than currying, and in my experience most of the time you'll only be dealing with one argument to pass piping anyway. Anonymous functions are fine for the cases you need more flexibility.

Are there any physicists out there who are reminded of abstract index notation for tensors?

A deal breaker, and just when I was starting to get excited!

Plenty of practical reasons for currying, but the biggest (imo) is for use with the pipe operator.

If they don't have partial application now, what are the odds they'll have it in the future?

As I mentioned in my other comment, they do have partial application with _, and it works like a charm for piping! It's automatic currying which is absent.

And that's fine, because currying forces you into impossible tradeoffs when choosing argument order.

But Haskell has nice little functions for switching argument order, and people can easily make them in other currying languages.