Single argument operator form?

Question

I've heard the explanation that functions like StringDrop[] are varargs and so that is why they do not have an operator form.

But when you are only using the single argument version, it seems well defined and quite ergonomic to me. Is there some other reason that operator forms like this aren't supported in the single argument case?

s = ImportString["./Arnold_Schwarzenegger 42
    ./George_W_Bush 530
    ./Jean_Chretien 55
    ./Jacques_Chirac 52", "Table"] // Dataset;
s[All, 1, StringDrop[#, 2] &] (* this works *)
s[All, 1, StringDrop[2]]      (* this doesn't work *)

Given the above example, the cited explanation is not clear, and I'm hoping a someone can comment.

Answer 1

We find that Drop and Take also lack an operator form. I believe this is because these functions have historically worked as identity when given a single argument, e.g. Take[{1, 2}] gives simply {1, 2}, and since the part specification of Take is often itself a List there is no way to differentiate reliably between a identity operation and an operator form.

I suspect that StringDrop and StringTake are simply following the syntax of Drop and Take in this regard in omitting an operator form, even though the nature of these functions makes the syntax unambiguous.