Recto – A Truly 2D Language

Summary

Recto — a truly 2D language Masato Hagiwara Open in Recto Pad Google Colab Github Recto Pad TL;DR Recto is a 2D programming language that uses nested rectangles as its core syntax, encoding structure and recursion directly in space instead of a linear stream of text. Recto explores new ways to write, parse, and reason about code—and even natural language—spatially. Introduction Open in Recto Pad Virtually all the languages we humans use—spoken, written, or artificial (such as programming languages)—are fundamentally one-dimensional. Words, phrases, and sentences are serialized into a linear sequence across time. This makes sense: language evolved from speech, where thoughts must be serialized into sound—a one-dimensional signal. But does a language have to be one-dimensional? The Kish Tablet, an early example of proto-writing using pictograms to convey meaning (source) Long before writing, humans used spatial representations as tools for thought. As Anne-Laure Le Cunff discusses in Thinking in maps, early symbolic systems like star charts in caves or medieval diagrams functioned not just as illustrations, but as visual languages for organizing meaning. From Lascaux to knowledge graphs, there’s a deep history of thinking in space—not just in time. When you consider what truly defines a language in the modern world, only two criteria stand out: Understandable — it must carry meaning for both humans and machines. Generable — it must be producible by both humans and machines. That’s it. There’s no inherent requirement that a language be linear, or pronounceable, or even textual. In the extreme, you could imagine a futuristic “language” that works like a smartphone app: you convey what you want to express—maybe through gestures or facial expressions—and the app outputs a structured grid of emojis or icons. If both sender and receiver (human or machine) understand it, communication happens—without sound, without linearity, and without words. There are already examples of ...