Sky is a new experimental programming language that compiles to Go, combining Elm's functional programming elegance with Go's pragmatism and ecosystem. Developed by an individual contributor, Sky aims to eliminate the traditional frontend/backend split by enabling developers to write fullstack applications in a single language that compiles to a single portable binary.

Inspired by Phoenix LiveView's server-driven UI approach, Sky features Hindley-Milner type inference, algebraic data types, and The Elm Architecture patterns. The language includes built-in support for server-rendered interactive UI through Sky.Live, eliminating the need for client-side frameworks or WebSockets. All tooling—compiler, CLI, formatter, and LSP—is self-hosted and written in Sky itself, producing a ~4MB native binary with zero Node.js dependencies.

The project emerged from frustration with the complexity of maintaining separate frontend and backend codebases, each with different type systems and build pipelines. After an initial attempt to compile to JavaScript proved problematic, the creator pivoted to Go as the compilation target, leveraging Go's fast compilation, single binary output, and mature ecosystem. The entire language was developed using AI-assisted tools like Claude Code, enabling rapid iteration that would have been impossible for a solo developer.