MacWire VS polysemy

Coming back to ZIO, besides learning the operators which ZIO has, there is not much to it and you have to embrace calling ZIO.x everywhere. The Layers in ZIO 2.0 are excellent and I believe that the creators want to trick us to write good OOP and we are one macro away from Springs Autowire. Perhaps even macwire is up to speed already, I didn't check for a long time.

You can have IoC without using a DI framework. You just pass the arguments manually. I've found that it works really well. If however that's not your preference there are a couple DI frameworks in scala such as: https://github.com/softwaremill/macwire and https://izumi.7mind.io/distage/index.html

Implement the application around https://github.com/softwaremill/macwire and hope the wiredInModule feature (which support dynamic loading) would be ported to Scala 3 soon.

Arguing for Macwire in Scala 3 is moot anyway, because it won't be available there: https://github.com/softwaremill/macwire/commit/e9281111d78a1beeb8950f367be18cbb67aef9fe

One easy reason is that macwire won't be available for Scala 3 (https://github.com/softwaremill/macwire#scala3) 😉

Thirdly, composing arbitrary effects without losing state is really, really difficult. Things are fine when you limit yourself to State and Reader, sure, but once you start with nondeterminism you’ll discover it’s shockingly easy to produce behaviors that are baffling unless you’ve spent a preposterous amount of time thinking about this stuff. (I’ve been bitten in prod by silent state-dropping bugs, and rarely have I been more flummoxed.) Consider this example, which produces silent changes in the semantics of <|> depending on whether you use it inside or outside of a higher-order effect. Every single effect library (besides the still-unreleased eff) gets certain combinations of effects + nondeterminism wrong. You could make the argument that most people don’t use nondeterministic monads, but eDSLs really shine when you have access to them, as you can turn a concrete interpreter to an abstract one fairly easily.

Looking for a few projects that make use of it, I found accelerate, hawk, polysemy and pretty-simple, so I'll be interested to poke around in their code and see how they have things set up.

Right, I think I'll just give it a shot to see. Polysemy is nice but I'm still having trouble getting what I want out of it (which may very well be entirely a fault of my own understanding)

Languages such as Koka only support algebraic effects, not scoping operations such as catch and listen. The Effect Handlers in Scope paper introduces scoping operations, which lead to the Haskell libraries fused-effects and polysemy, but they turned out to have some weird semantics. eff is her effort to fix that.

Looking at the interpreter for Reader might give some clues if this doesn't work. https://github.com/polysemy-research/polysemy/blob/master/src/Polysemy/Reader.hs#L38-L45

*But I'm not terribly well versed in Scala's other DI offerings. I came from Haskell and didn't find anything in Scala that clicked with me until I found ZIO. It reminded me a lot of my favorite way of writing Haskell programs (https://github.com/polysemy-research/polysemy)—albeit with a completely different implementation.