I don't know fish, but I don't consider zsh a step in the right direction, as it tries to be just a cleaned up Bash, which is not enough.
There is a general problem in the fact that a radical evolution of glue languages wouldn't be popular because devs rather use Python, and small evolutions wouldn't be popular (ie. zsh), because they end up being confusing (since they're still close to Bash) and not bringing significant advantages.
I'm curious why there haven't been attempts to write a modern glue language (mind that languages like Python don't fit this class). I guess that Powershell (which I don't know, though) has been the only attempt.
zsh is not a "cleaned-up bash"; it's more of a clone of ksh (closed source at the time), with some csh features added in, as well as their own inventions. bash and zsh appeared at roughly the same time, many features were added in zsh first and added to bash later (sometimes much later, and often never).
This is kind of a good example of what I meant when people conflate "bash" with "shell".
As for your larger point: I kind of agree, but I think what zsh offers is the advantages of shell scripts with compatibility with existing scripts while still improving on it. That said, I believe oil also offers compatibility, but I haven't had the chance to look deeply in to it; just haven't had the time, and wanted to wait until it's stable (maybe it is now?)
Perl was initially invented as the "modern glue language" to replace shell. It's fallen a bit out of fashion these days though, and to be honest I never cared all that much for Perl myself either. Raku looks nice though. TCL also works well as a kind of "glue language", although it has some really odd behaviour at times due to everything being a string and I know some people hate it with a passion, but it always worked fairly well for me. But that has also fallen out of fashion.
I've also been told PowerShell is actually quite nice and has interesting concepts (and now also open source, and you can run it on e.g. Linux), but I could never get over the verbosity of it all. I'm an old unix greybeard and I want my obscure abbreviations dammit!
The verbosity of PowerShell is overstated I think. You easily make POSH look as gnarly and esoteric as Bash if you so desire. That said, the majority of heavy lifting in POSH is done via methods these days (vs cmdlets). Your initial API query to snag the JSON might be via a cmdlet, but after that, you're slicing and dicing with real data structures. You can interact with them without having worry about whitespace or structure (meaning complex loops can easily be written on the command line without worrying about indentation).
It's a little more wordy if you're use to C or Bash. But hands down it's one of my favorite languages for slicing dicing data. No need for 3rd party libraries or binaries. No need to learn a bunch of weird awk/jq syntax which is only useful for those two tools (yay, lets learn 3 language instead one?). Plus, most of the structure translates over to C#, and you can integrate C# code directly into your POSH code if desired, as well as access pretty much any low level C# methods directly.
Working with strings? Pretty much any/every tool you could want to slice and dice strings.
The POSH REPL is amazing. You have far more flexibility around interacting with the command line than you do with Python. It's both a shell and a true language. As with any language, there are ISMs, but far fewer footguns than any other language I've spun up.
Cross platform as well with 6.0+
Intellisense ON the commandline (did I mention the awesome REPL?). Hands down one of the best built-in parameter/args/help parsing I've encountered across any language. Debugging? Amazing in vscode. And can be done strictly from the commandline as well (dynamic breakpoints? You've got it, drop you right into your catch block with an interactive shell so you can see the current status of any/all variables and manipulate them live and resume if desired)
Okay, I'm done shilling for POSH. It's hands down one of my favorite shells/languages for doing POC work, or writing utility functions. Treat it more like Python than bash. But realize that you can easily use that Pythonic-esque code right inside your shell.
Just so you know. You can abbreviate almost anything in powershell or make your won aliases. I love Powershell, hands down best investment in my personal career was to really learn and understand Powershell.
I'm a Unix user and spent almost all of my professional career in bash, and switched to Powershell for my interactive shell a few years ago.
The nice thing with Powershell is that it's not verbose, but the arcane abbreviations are actually quite a bit easier to remember and discover than bash. What mixes people up is that in documented examples and reusable scripts, it makes sense to use the full, canonical name, which looks aesthetically different coming from a Unix background.
Here's what it might actually look like to check a JSON file that has an array of file metadata objects, and delete the ones that have been processed (this includes one user-defined alias, cfj, for "ConvertFrom-Json"):
gc queue.json | cfj | where status -eq processed | ri
That seems pretty NON-verbose to me, equivalent to how you'd approach this in bash. Do you have jq installed? If you do, perhaps:
If you don't have jq I think this gets much longer and is either really brittle (you're doing some kind of adhoc parsing that's terrible) or really heavyweight (like pulling in a pure bash JSON library--they exist) or you're using a one-liner from another programming language (Ruby, Python, something). Or maybe you'd complain to whatever was writing 'queue.json' and ask for a friendlier format, like something terrible and one-off you invented because it's easy to "parse" with awk?).
It's even better if you're dealing with network resources:
What probably makes you think Powershell is verbose is that, although that's how I type Powershell, it's not how I document it. If I were documenting it for someone else's use, or incorporating that pipeline into a script or module, I'd write it like this:
So it's not like it's verbose while you're using it, but verbosity is something you can reach for for clarity when it's desirable. Likewise, you can see the consistent relationship between these commands and their aliases: gc -> Get-Content, cfy -> ConvertFrom-Yaml, ri -> Remove-Item. So you have options for how verbose you need to be. I find it's very useful to have a spelled-out version for commands I don't use all the time, like 'Get-EC2Instance', and consistent verbs so I can make reasonable guesses at the command name for things I'm even less familiar with.
I didn't want to clutter this with too many examples but I'll reiterate that Powershell is a shell. It invokes your Unix commands just fine. For example, if you forgot what the option to Get-Date is, to get a Unix-style timestamp (it's 'get-date -uf %s' so not exactly hard to use): you can just type 'date +%x'. In the example above, I could have used 'cat' and 'xargs rm' instead of 'gc' and 'ri'. So it's not like you have to buy the whole kit and kaboodle right away, either.
zsh is, historically, a step from csh-like interactive shells in the direction of Bourne/ksh compatibility. It's easy to get the impression that zsh is a newer development than bash, but they're actually contemporary—bash rode on the popularity of GNU in the 90s, despite being a "small evolution" (frankly, a step back) compared to the ksh lineage.
tcsh was the default shell before that, and it didn't help much with its popularity, and for interactive usage tcsh can do most of the things bash can and is mostly okay (not scripting though).
I think being the de-facto default on Linux as part of "GNU plus Linux" has more to do with it.
There is a general problem in the fact that a radical evolution of glue languages wouldn't be popular because devs rather use Python, and small evolutions wouldn't be popular (ie. zsh), because they end up being confusing (since they're still close to Bash) and not bringing significant advantages.
I'm curious why there haven't been attempts to write a modern glue language (mind that languages like Python don't fit this class). I guess that Powershell (which I don't know, though) has been the only attempt.