Self-authoring agent skills on the BEAM (LFE): compile an LLM snippet to a module, hot-load it, and every agent can call it. Companion to josefrichter.design/blog/skills-are-modules

skills-are-modules-demo.lfe

(defmodule crowd-demo
  (export (run 0) (install-skill 1) (bot-loop 1)))

;; ---------------------------------------------------------------------------
;; A bot is a process. It waits for work, calls whatever skill it's asked to,
;; and reports the result back. It has NO built-in knowledge of any skill.
;; ---------------------------------------------------------------------------
(defun bot-loop (name)
  (receive
    (`#(call ,from ,mod ,fun ,args)
     (let ((result (try
                     (tuple 'ok (apply mod fun args))
                     (catch
                       (`#(,_class ,reason ,_stack)
                        (tuple 'undefined reason))))))
       (! from (tuple name result)))
     (bot-loop name))
    ('stop 'ok)))

(defun spawn-bot (name)
  (spawn 'crowd-demo 'bot-loop (list name)))

;; Ask a bot to run a skill, wait for its reply, return it.
(defun ask (pid name mod fun args)
  (! pid `#(call ,(self) ,mod ,fun ,args))
  (receive
    (`#(,name ,result) result)
    (after 2000 #(error timeout))))

;; ---------------------------------------------------------------------------
;; Installing a skill: the "model" handed back source text. We read it into
;; forms (code is data), compile those forms to a real BEAM module, and
;; hot-load it into the running node. From now on EVERY process can call it.
;; ---------------------------------------------------------------------------
(defun install-skill (source)
  (let* ((`#(ok ,forms) (lfe_io:read_string source))
         (`#(ok (#(ok ,mod ,bin))) (lfe_comp:forms forms '())))
    (code:load_binary mod "nofile" bin)
    mod))

;; ---------------------------------------------------------------------------
;; The demo.
;; ---------------------------------------------------------------------------
(defun run ()
  ;; Two independent bots. Alice will "learn" a skill; Bob never touches it.
  (let ((alice (spawn-bot 'alice))
        (bob   (spawn-bot 'bob)))

    (io:format "1. Before anyone learns anything~n" '())
    (io:format "   bob asked to run web-search:query -> ~p~n~n"
      (list (ask bob 'bob 'web-search 'query (list "beam vs node"))))

    ;; The source a model would have written, as plain text.
    (let ((skill-source
            "(defmodule web-search
               (export (query 1)))
             (defun query (q)
               (++ \"results for: \" q))"))

      (io:format "2. Alice installs the skill the model wrote~n" '())
      (let ((mod (install-skill skill-source)))
        (io:format "   hot-loaded module: ~p~n~n" (list mod)))

      (io:format "3. Alice runs it (she authored it)~n" '())
      (io:format "   alice -> ~p~n~n"
        (list (ask alice 'alice 'web-search 'query (list "beam vs node"))))

      (io:format "4. Bob runs the SAME skill - never installed it, never restarted~n" '())
      (io:format "   bob   -> ~p~n~n"
        (list (ask bob 'bob 'web-search 'query (list "beam vs node"))))

      (! alice 'stop)
      (! bob 'stop)
      'ok)))