Read a language the way it's built. Small, open tools for learning languages, where readings, conjugations and grammar points are worked out and checked rather than guessed, so what you learn holds up.

• Kotone 言音 · repo
  Learn Japanese through music. A 550 KB Mac lyrics player: furigana and a Chinese translation beside every line, and any line taken apart into its phrases, words and grammar. Your own Codex annotates the songs; a deterministic checker re-derives every reading and conjugation it writes.
• Typed Japanese · repo
  Japanese grammar as TypeScript types. A 47-chapter course, in English and 简体中文, where every sentence is a type the compiler checks.
• Typed Korean · repo
  Korean grammar, the same way.

A line from Frieren, ヒンメルならそうした (辛美尔的话也会这样做的), written so the compiler can check it:

type ヒンメル = ProperNoun<"ヒンメル">;
type する = IrregularVerb & { dictionary: "する" };
type そうした = DemonstrativeAction<Demonstrative & "そう", する, "Ta">;
type ヒンメルならそうした = ConditionalPhrase<ヒンメル, "なら", そうした>;

const quote: ヒンメルならそうした = "ヒンメルならそうした"; // ✓
const wrong: ヒンメルならそうした = "ヒンメルならこうした"; // ✗ TS2322

Whoever writes an annotation, a person or a model, has to make it add up: the conjugation, the reading and the grammar are derived again and compared. That makes these tools useful as

• ways for learners to see how a sentence is built, and why;
• an intermediate format that keeps AI-written grammar honest;
• grammar checkers, and a footing for typed natural-language tools.

For collaborations, contributions or other questions: [email protected].