There's something of a tradition of REPLs having personalities in lisp. I've seen Common Lisp tools (e.g. slime/sly) and Clojure (e.g. cider) say encouraging things, but Fennel is almost judgemental :)
miniblog.
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Writing an IRC server, exploring object systems, and enabling hot reloading for clients: https://technomancy.us/197 (in Lua and Fennel)