pAIrens

A Lisp REPL you and Claude share. pAIrens is a mod for Claude Code that puts a REPL beside the chat, connected to your live Lisp image. You both use it, and each of you sees what the other did.

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CL-USER> (defun greet (who) (format t "Hello, ~a!~%" who) (length who))
⇒ GREET
CL-USER> (pairens:claude "what does GREET return, and why?" (greet "Lisp"))
⇒ :SENT
✻ Claude  It returns 4: the last form is (length who). The greeting
          is printed as a side effect; FORMAT's NIL is discarded.

What it does

REPL beside the chat

A pane with your history, output, values and errors, and an input pinned at the bottom. Each tab is a session with its own package.

Ask from the REPL

(pairens:claude "…") sends a question, a value too if you like, and the answer lands back in your REPL. Works from SLIME too.

Claude uses it too

Claude inspects and evaluates code in your running image, with every eval shown and marked. Long jobs go in a session of its own.

You set the rules

Choose ask, auto or read-only to decide how Claude's evals run.

Languages

Common Lisp over Swank. Available now; pAIrens can launch SBCL for you or connect to a running Swank.
Clojure / ClojureScript over nREPL. Coming soon.
A REPL in its own browser window. Coming next.

Install

In a Claude Code terminal session:

/plugin install pairens --marketplace megajess/pairens

In the Claude desktop app, click + next to the prompt box, then Plugins. Choose Add marketplace with megajess/pairens, then Add plugin. You'll need Node.js, plus SBCL and Quicklisp if you want pAIrens to start Lisp for you. The README has the details.

Your subscription, your session

pAIrens works inside the Claude Code session you're already signed in to. It needs no API key and never sees your credentials. Questions you ask from the REPL are ordinary turns in that session.