Comment by PufPufPuf

Definitely Opa: http://opalang.org/

In 2011, before TypeScript, Next.js or even React, they had seamless server-client code, in a strongly typed functional language with support for features like JSX-like inline HTML, async/await, string interpolation, built-in MongoDB ORM, CSS-in-JS, and many syntax features that were added to ECMAScript since then.

I find it wild how this project was 90%+ correct on how we will build web apps 14 years later.