Life & fun · September 29, 2010
Koi - a programming language that teaches language implementation.
Koi - a programming language that teaches language implementation. launched on September 29, 2010 with 70 votes, #1 of 24 launches that month and more than 90% of that year's launches. The site was still online in September 2026, 16 years on.
In plain words
Koi is a programming language designed to teach how language implementation works. Written in Ruby rather than a low-level language, it prioritizes clarity and accessibility over performance, making its implementation straightforward to understand and follow. It is intended for people who want to learn the fundamentals of building a programming language by studying how Koi itself is constructed.
written from the facts on this page · September 2026
From the sources
Several months ago I started on a quest to learn more about how programming languages work internally. Today I am releasing my first programming language: Koi. Koi is designed, above all else, to be a language whose implementation demonstrates the basics of how to build a language in a straight-forward way. Most programming language implementations are written in low-level languages like C in order to maximize performance, and this generally makes them very opaque and difficult to follow. In order to avoid this problem Koi is written from the ground up in Ruby to make sure that the implementation language never gets in the way of the intent of the code. Koi will likely never be suitable for…from thingsaaronmade.com
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Koi Editor AlphaSep 2026 · koieditor.com · ▲6Koi is a minimalist code editor. It makes typing feel instant. No distractions. Just fast, keyboard-first coding.
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