... and many also have succeeded. fish would not be as popular as it is otherwise, other alternative shells that break bash compatibility are being worked on and are gaining traction, elvish, nushell, murex...
mixing shells is not as hard as some people claim. it's like switching programming languages. i do that all the time. but then, i avoid bash scripting as much as i can (or shell scripting in general). if you actually enjoy bash scripting then switching may be harder.
I might be in a minority, but I actually prefer fish as an interactive shell and bash (or plain /bin/sh) for scripting, if anything because that's what I'm used to :), and it's portable
I did the same thing but I'm now pushing it a bit further: POSIX shell rather than Bash for scripts. If what I'm doing can't be done with that it suggests that I should probably just write it in Python or Perl instead.
Fish scripting is limited to functions/aliases and this works out well since they're easy to read and tweak over time.
that's a sensible approach. fish does have the best interactive interface out there. i switched to elvish because i like it better for complex commandlines, mainly because it has support for more advanced data structures and also integrates json well. (and i realized that using braces for code blocks is nicer in a complex one line command, but both are better than bash for interactive use)
Really like using fish as my interactive shell too.
Many have succeeded writing functional alternative shells for sure, but none have replaced bash at any meaningful scale.
disagree. the fact that i can see more and more support for fish and also start seeing support for elvish shows that those alternative shells have reached a scale meaningful enough that tool developers actually consider it worth their effort to support them. what else is that if not evidence that alternative shells have reached a meaningful scale?
before fish basically noone dared to break bash compatibility. zsh is bash on steroids and other incompatible shells like csh, tcsh, ksh, etc were dead ends in that they kept a niche status.
fish was the first shell to break out of that and actually get noticed and gain a following. i believe that all other alternative shells after fish were encouraged only because of fish's popularity.