https://github.com/lmorg/murex

It currently has:

* Proper error handling (eg try and catch blocks)

* unit testing and debugging frameworks to help with development and maintainability

* data-type aware, including complex types like how CSV, JSON and YAML are all handled as memory structures and thus the same tools can query any structured data format without understanding it's contents

* while still ostensibly working the same way as a traditional POSIX shell

There's also some work on improving the REPL experience too where I've included:

* automatic man page parsing for flags

* a "tool tip text" like hint line which tells you where commands reside on the fs, what it does, etc. Which is handy if you're trying to debug an existing commend.

* if you paste multiline text into the console you get offered a chance to preview the text before executing it (handy if, like me, you're pretty useless at copy/pasting content reliably)

* a package management system so you know exactly which functions and imported scripts are loaded from which sources (no more "where did that autocomplete suggestion / alias / etc get loaded from?"

There's a few other features like support for events and such like, but they're not yet documented.

The shell is currently beta but I've been using it as my daily driver for about 18 months now. There are still quite a few bugs, plenty of places where code needs to be rewritten for performance and lots of stuff isn't yet documented (though the documentation is pretty good already considering it's only me working on it). So don't expect a finished product. However I do think I'm at the stage where I'm ready for more users to have a play and I welcome PRs, issues raised, general comments and feedback, etc.

# end of shameless self promotion :D