[willghatch]

Since everybody else is peddling their better shells, I'll drop a plug for mine: https://rash-lang.org

It's a shell embedded in the Racket programming language. If you're familiar with Xonsh, it's similar, but both more powerful and less polished. It allows easy, recursive mixing of shell code (not posix compatible, but with a similar feel) and Racket. Its interactive mode is not polished (I need to write a better line editor), but it works, and it's great for programming.

I haven't worked on it much lately (I need to wrap up other things to finish my PhD), but this weekend I added support for user-programmable substitutions with automatic cleanup. As an example, beyond common substitutions like process substitution (IE <() and >() in bash), I added a demo “closure substitution” form that allows you to send Racket functions to `find -exec`. Importantly, this is something that a user could add, because Rash is super extensible and malleable.

Shell is a great DSL, but there are huge advantages to having an embedded DSL rather than a stand-alone DSL. Rash inherits all the cool features of Racket and can be mixed with other Racket languages (eg. Typed Racket, Honu, etc), has advanced features like first-class delimited continuations and the world's most advanced macro system (which makes Rash possible), and any shell script can import functions from Racket's catalog of third-party packages. Embedded shells like Rash allow a shell script to be copied from interactions like you do with Bash, but then grow past the “rewrite in Python” stage gradually with no rewrite -- just a gradual transition from being more shell code to being more “normal” code.

Though I'm kicking myself for continually not getting around to rewriting all the documentation, which is still very poor.