I bet yash is great, sorry for distracting from the topic, but since you asked...

It's not one killer feature, but it's a lot of small things that add up to this feeling that POSIX shells are stuck in a rut and that a better world is possible.

I'm going to use docker output as an example. I know that you can ask docker for json and then use jq, but let's pretend that what you're working with isn't so friendly as docker. Here's the output of "docker ps", a string:

    CONTAINER ID   IMAGE            COMMAND                  CREATED       STATUS       PORTS                   
    786fc8348b7a   postgres:12.6    "docker-entrypoint.s…"   9 hours ago   Up 9 hours   127.0.0.1:5432->5432/tcp

I'm not proud of it, but I used to write bash scripts which looked like this:

    line=$(docker ps | grep postgres)
    echo $line | awk '{print $2}'
    echo $line | awk -F 'ago' '{print $2}' | sed 's/hours.*/hours/'

to get output like this

    postgres:12.6
    Up 9 hours

In nushell, that's this (notice that it gets the whitespace right, which is more than I can say for awk).

     $ docker ps | detect columns --guess | where ($it.IMAGE =~ postgres) | select IMAGE STATUS

    ╭───┬───────────────┬────────────╮
    │ # │     IMAGE     │   STATUS   │
    ├───┼───────────────┼────────────┤
    │ 0 │ postgres:12.6 │ Up 9 hours │
    ╰───┴───────────────┴────────────╯

This the part where somebody says "powershell does that too", but check out this stackoverflow post on just how that might be done: https://stackoverflow.com/questions/47335781/extract-columns... It's not exactly wow material.

Powershell feels to me like it's made by people who want all data to be structured, and who expect the app to do the work of structuring it for them. nushell feels like it's made by people who understand that text is king, and who are willing to attempt taming that beast as-is.

Plus there are a lot of batteries-included things that just feel nicer. Like if you want to make an http post request, the command is "http post". Of course you can still use curl, but I feel like this is so much more readable:

      $ let token = "REDACTED"
      ( http post
          -H {Circle-Token : $token}
          --content-type application/json
          "https://circleci.com/api/v2/project/gh/job/myproject/pipeline"
          {  branch: "main",  parameters:  { action: "dothething" }}
      )

The built in help is excellent (try "help http post"), and the error messages are very pleasant:

    $ 5 + "5"

    Error: nu::parser::unsupported_operation
    × addition is not supported between int and string.
       ╭─[entry #208:1:1]
     1 │ 5 + "5"
       · ┬ ┬ ─┬─
       · │ │  ╰── string
       · │ ╰── doesn't support these values
       · ╰── int
       ╰────

I dunno, it's just nice. I'd be much happier teaching a bunch of scientists to use nushell than I am when teaching them to use bash. When I try to do the latter I feel like I just stepped out of a time warp from the 60's and they think I'm here to punish them.