Sure, I guess if they feel the open source versions of Swift's standard library are functional enough to release production quality software.

Keep in mind, the UI code will be completely custom for Windows though.

> the UI code will be completely custom for Windows though

So Swift programs on Windows will actually look and feel like a Windows program? Good.

Sorry to disappoint but :

> After an extensive discussion, we ended up with Electron as the front-end part of future Spark for Windows.

Apparently they use a Swift plugin for Nodejs