Lisp | Tlen

That's it. 15 lines of Lisp, and you have a protocol server. You might think: "A loop that reads and writes? Python can do that."

;;; tlen.lisp - A minimalist Telnet echo server (require :usocket) ; A portable socket library (defun handle-client (stream) "Echo back whatever the client sends, but shout it in uppercase." (loop :for line = (read-line stream nil) :while line :do (write-line (string-upcase line) stream) (force-output stream))) lisp tlen

For a Lisp REPL, this is home turf. Lisp doesn't care if you're crunching matrices, parsing XML, or listening on port 23. The code looks the same. Let's build a toy Telnet server in Common Lisp. We'll call it tlen.lisp (see what I did there?). That's it

Note: "Tlen" is not a standard term in mainstream Lisp literature (Clojure, Common Lisp, Racket, etc.). It is most likely a typo or autocorrect error. Based on common search patterns, I have assumed you meant one of three things: (Common Lisp Object System), "TCO" (Tail Call Optimization), or "TELNET" (network protocols). Python can do that