Oilsh has focused more on backwards compatibility. This approach of adding a small functional language is interesting. The author seems to have done an elegant job with the syntax. Adding this to my list of things to download and play with.
Rash, the Racket Shell, does something similar to this: https://docs.racket-lang.org/rash/index.html
Es shell is similar but in a less lispy, more bash style.
xonsh does the same thing for sh and python.
This is great! Are there any other shells like this? I like the idea of something backwards compatible with bash.