Console

Browser console logging as an effect. The app is pure and the compiler enforces it, so logging is data like every other observable effect: return Console.log(...) in the effect list from init or update. Messages queue host-side and the JS runtime drains the queue to console.log after each entry call.

There are two console streams. Console.log is the intentional app logging effect: you own the message, and it lands in console.log. The dbg expr statement is the development printf: it is pure to the effect system, so it works anywhere in init, update or render, its output format belongs to the compiler (the inspected value), and it lands in console.debug, which files under the Verbose level in devtools. Statement form only, x = dbg y is not supported.