See https://en.m.wikipedia.org/wiki/Uniform_function_call_syntax - the examples section has two side by side. The Nim language version is also pretty readable even if you're not familiar with it.

As for idup... The first several search results for "dlang idup" are all useful.

> I really want to look at the code and be able to know straight away what it does, or have a rough idea.

I presume you really don't like perl, ML based (ocaml, f sharp, rust) Haskell or K.

I love Perl[1] and OCaml. I dislike the rest. It depends on the task.

> As for idup... The first several search results for "dlang idup" are all useful.

Yes, I am sure it was, I am sure an LLM would have helped too, but I think that is besides the point here.

Is it beside the point? Looking at that perl example:

$string =~ s/\d+/NUM/g;

I don't have a clue what is going on. Sure, I see the regex, but what is =~ doing?

There's only so far you can stretch most languages before you need to actually put in effort to learn them.

	▲	johnisgood 8 hours ago \| parent [-]
		"=~" is the operator testing a regular expression match. It should be obvious, because on the right side you see regex, and you ought to know what "=" or "==" does. FWIW, I knew this as a kid, too, despite knowing absolutely nothing about the language at the time. Anyways, you should read https://news.ycombinator.com/item?id=44463391 if you care about why I dislike the way D does it.