Amazing how people still put up with this nonsense. Bash really has no place in this age.

What's a decent replacement shell? Sometimes I think there should be one, with all backwards compatibility for if/looping thrown out, but still adhering to the core concept of mostly being made of a handful of builtins and otherwise executing commands (i.e., without having to type system("") or exec("") etc. to execute commands).

hnlmorg

I've written one specifically to solve if and looping: https://github.com/lmorg/murex (docs: https://murex.rocks)

Others I've not used are oil shell, which aims to be a better Bash. Elvish, which has a heck of a lot of similarities with my own project (and is arguably more mature too). There are REPL shells in LISP, Python and all sorts too.

So there are options out there if you want a $SHELL and happy to break from POSIX and/or bash compatibility.