The purported benefits of effect systems

Two language designers staged a nerdy duel over “effect systems,” which are like permission slips for your functions: they say up front if your code might talk to the internet, read your files, or print to the screen. The idea shows up in newer languages like Unison, Koka, and Flix, and promise safer, more testable code. The piece walks through how you can stack multiple “effects,” and even do type-level math to add or subtract them. But the real fireworks? In the comments, of course.

The top vibe: a split between “this fixes real-world pain” and “this is academic cosplay.” One loud cheer came from folks arguing that effects make the safe path the easy path, especially for sandboxing build scripts and writing tests. User curtisf summed it up as the “physics” of coding rewarding laziness—so make laziness safe. On the other side, skeptics rolled their eyes at scary-looking types, sniping that it’s just a fancy way to say “this might throw or do I/O,” and joking that “my boss won’t approve a rewrite in Koka.” Memes flew: “choose your fighter—wizard spells (handlers) vs permission slips (effects),” plus monad flashback jokes and “row math” screenshots. The crowd’s split, the takes are spicy, and the future of safer-by-default code has everyone hitting refresh.