--- title: An Agent in 100 Lines of Lisp, or How my Prof was Right... description: A developer revisits Lisp 25 years after an AI course and builds a fully functional AI agent in ~100 lines of Common Lisp. The agent loop is implemented as a... canonical: https://daily.dev/posts/an-agent-in-100-lines-of-lisp-or-how-my-prof-was-right---just-25-years-early-htvbgsbze twitter:card: summary_large_image twitter:site: @dailydotdev og:type: website og:site_name: daily.dev og:title: An Agent in 100 Lines of Lisp, or How my Prof was Right - Just 25 Years Early | daily.dev og:description: A developer revisits Lisp 25 years after an AI course and builds a fully functional AI agent in ~100 lines of Common Lisp. The agent loop is implemented as a... og:url: https://daily.dev/posts/an-agent-in-100-lines-of-lisp-or-how-my-prof-was-right---just-25-years-early-htvbgsbze og:image: https://api.daily.dev/og/posts/HTvbGSBZe.png og:image:alt: An Agent in 100 Lines of Lisp, or How my Prof was Right - Just 25 Years Early og:image:width: 1200 og:image:height: 630 og:locale: en --- > ## Documentation Index > Fetch the complete documentation index at: https://daily.dev/llms.txt > Use this file to discover all available pages before exploring further. # An Agent in 100 Lines of Lisp, or How my Prof was Right - Just 25 Years Early **[Hacker News](https://daily.dev/sources/hn)** · 10 min read · 0 upvotes · 0 comments ## Summary A developer revisits Lisp 25 years after an AI course and builds a fully functional AI agent in ~100 lines of Common Lisp. The agent loop is implemented as a recursive function rather than a state machine. The key insight is using Lisp's homoiconicity to give the model a single tool — eval — letting it write and execute arbitrary Lisp code at runtime. This allows the agent to dynamically build its own capabilities: it spontaneously wrote a Brave Search HTTP client into the live image when given an API key. Memory is implemented as JSON serialization of the message list, and since function definitions live in the transcript, the agent can re-hydrate its own skills from conversation history on restart. The post reflects on how Lisp's 'code is data' philosophy maps surprisingly well onto modern agent architectures. ## Full article daily.dev links to this article rather than hosting it. Read it at the original source: ## Similar posts on daily.dev - [There Is No Magic: An AI Agent in 60 Lines of Python](https://daily.dev/posts/there-is-no-magic-an-ai-agent-in-60-lines-of-python-t6ewwomux) · Planet Python · 3 upvotes · 2 comments - [Why I Love Agent Pi](https://daily.dev/posts/why-i-love-agent-pi-x0gusbtjt) · BirkeyCo · 2 upvotes · 0 comments - [Building AI agentes in practice with Clojure](https://daily.dev/posts/building-ai-agentes-in-practice-with-clojure-ucsoiggp2) · Nubank · 1 upvotes · 0 comments - [The Emperor Has No Clothes: How to Code Claude Code in 200 Lines of Code](https://daily.dev/posts/the-emperor-has-no-clothes-how-to-code-claude-code-in-200-lines-of-code-ip0liwwaj) · Hacker News · 1 upvotes · 0 comments --- Tags: [#llm](https://daily.dev/tags/llm), [#ai-agents](https://daily.dev/tags/ai-agents), [#lisp](https://daily.dev/tags/lisp) [View this post on daily.dev](https://daily.dev/posts/an-agent-in-100-lines-of-lisp-or-how-my-prof-was-right---just-25-years-early-htvbgsbze) ```json {"@context":"https://schema.org","@graph":[{"@type":"Organization","@id":"https://daily.dev/#organization","name":"daily.dev","url":"https://daily.dev","logo":{"@type":"ImageObject","url":"https://daily.dev/apple-touch-icon.png","width":180,"height":180},"sameAs":["https://twitter.com/dailydotdev","https://github.com/dailydotdev","https://www.linkedin.com/company/daily-dev-ltd"]},{"@type":"WebSite","@id":"https://daily.dev/#website","url":"https://daily.dev","name":"daily.dev","publisher":{"@id":"https://daily.dev/#organization"},"potentialAction":{"@type":"SearchAction","target":{"@type":"EntryPoint","urlTemplate":"https://daily.dev/search?q={search_term_string}"},"query-input":"required name=search_term_string"}}]} {"@context":"https://schema.org","@type":"TechArticle","headline":"An Agent in 100 Lines of Lisp, or How my Prof was Right - Just 25 Years Early","url":"https://daily.dev/posts/an-agent-in-100-lines-of-lisp-or-how-my-prof-was-right---just-25-years-early-htvbgsbze","mainEntityOfPage":{"@type":"WebPage","@id":"https://daily.dev/posts/an-agent-in-100-lines-of-lisp-or-how-my-prof-was-right---just-25-years-early-htvbgsbze"},"datePublished":"2026-07-12T05:44:19.454Z","dateModified":"2026-07-12T05:45:47.150Z","description":"A developer revisits Lisp 25 years after an AI course and builds a fully functional AI agent in ~100 lines of Common Lisp. 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