Partly for inspiration and partly for reference:

• https://github.com/rain-1/single_cream
  • Has a nice idea of "(sort-by fun list)"
  • Has some nice test-cases.
• https://haltp.org/posts/owl.html
  • Has a modular setup - see also Allow "require" or "import" #114
• https://github.com/thesephist/klisp
  • Has "sum" and "mean".
• https://github.com/eigenhombre/l1
  • Has a nice idea of (comment) - Would be nice to automate our API docs
  • Has a cute idea of unbinding things for fuzzing.
    • https://github.com/eigenhombre/l1/blob/master/examples/fuzz.l1
• https://github.com/candid82/joker
• https://github.com/zhemao/glisp
  • Has bit operations, shiftleft, etc.
  • Also has channels and coroutines as well as pre/post hooks (though these seem to be undocumented).