I hadn't really looked at Nushell, but it (process control) is definitely something I plan to improve in Aria (https://github.com/egranata/aria/issues/21). Right now I have a simple system() wrapper, but not much in terms of advanced subprocess control. Maybe worth investing some time in cleaning up?

I have tried to fill the niche of "scratch my itches, please", which means Aria is intended to feel smooth, pleasant and simple to write in. There are still things I want to improve before calling it a 1.0, but the general theme is, a general purpose scripting language with just enough structure and as little ceremony as possible.

It may be that I struck the wrong balance somewhere (and I know of a few places, e.g. operator overloading - I plan to rewire the syntax), and that would be great to get eyes on and get feedback!