And Lisp? Lisp is the perfect knife for cutting through that stream. Modern APIs are obsessed with structure. GraphQL schemas, Protobuf definitions, OpenAPI specs. It's powerful, but it's heavy.
(defun start-tlen-server (&optional (port 2323)) "Start a Telnet-like server on PORT." (let ((listener (usocket:socket-listen "0.0.0.0" port))) (format t "~&TLEN Server listening on port ~A~%" port) (loop (let ((client-stream (usocket:socket-stream (usocket:socket-accept listener)))) (format t "~&New connection from ~A~%" client-stream) ;; Handle one client, then close (simple for demo) (handler-case (handle-client client-stream) (error (e) (format t "Error: ~A~%" e))) (close client-stream))))) lisp tlen
;;; 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))) And Lisp
I recently spent a weekend revisiting Telnet, not as a sysadmin, but as a Lisp programmer. Why? Because stripping away TLS, JSON, and REST frameworks reveals something beautiful: GraphQL schemas, Protobuf definitions, OpenAPI specs
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."
Telnet (and its modern descendant, the raw TCP socket) is minimalist. You open a port, you read bytes, you write bytes. 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).