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tech 12 July 2026

An Agent in 100 Lines of Lisp: Revisiting Symbolic AI Roots

Rediscover the power of Lisp to create AI agents. A return to basics that might just be the key to your next tech project.

Article inspired by the original source
An agent in 100 lines of Lisp ↗ thebeach.dev

Introduction

Artificial Intelligence (AI) has come a long way since the early days when Lisp was considered the go-to language. Today, as we are overwhelmed by statistical methods and deep learning, it is easy to forget the symbolic roots of AI. But what if we could combine the simplicity and elegance of Lisp with the power of modern agents?

Why Lisp?

Created in the 1950s, Lisp was one of the first programming languages used for AI. Its ability to manipulate symbols and recursively handle lists makes it an ideal choice for expert systems and theorem provers. With just 100 lines of code, it is possible to create a functional AI agent in Lisp, illustrating its power and simplicity.

A Concrete Example

Let's take the example of a simple conversational agent. The agent receives messages, sends them to a model, and based on the response, either replies or executes a command. In Lisp, this translates to an elegant recursive function that intuitively handles messages and tool calls:

``lisp (defun agent-loop (messages) (let* ((message (ref (call-model messages) "choices" 0 "message")) (tool-calls (gethash "tool_calls" message))) (if (and tool-calls (plusp (length tool-calls))) (agent-loop (append messages (list message) (map 'list #'execute tool-calls))) message))) ``

The Power of Simplicity

The elegance of Lisp lies in its ability to express complex concepts with minimal syntax. This allows developers to focus on the logic and structure of the agent rather than implementation details.

Use Case

A concrete use case could be developing an internal recommendation system for a tech company. Using Lisp, a developer can quickly create a functional prototype that analyzes user preferences and provides personalized recommendations.

The Revival of Lisp

Although Lisp has been overshadowed by more modern languages, its unique approach and ability to handle symbolic tasks make it a valuable tool for certain AI projects. With the renewed interest in autonomous agents and symbolic manipulation, Lisp might well experience a revival in the tech world.

Conclusion

Lisp, with its simplicity and elegance, offers a refreshing perspective on creating AI agents. Whether you are developing a recommendation system or a simple chatbot, returning to basics with Lisp might be just what you need for your next project.

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