Enjoyed this wiki post by the author of Garnet on effect systems: [[PonderingEffects]]. What I liked is that it doesn't just describe the design space: it's honest about what the author finds confusing or unconvincing, including a skeptical take on algebraic effect handlers specifically. The Lobsters thread is worth reading too; someone points out that what the post calls “effects on data” is already studied under the name coeffects, which was news to me.

Reading this also made me realize I've had a soft spot for dynamic scoping/implicits for a long time… probably since I first used @mitsuhiko's Flask, where the request context object was just there without you having to pass it around. Felt like magic, then felt like a footgun, then felt like a reasonable tradeoff again. Python has since put contextvars in the standard library, which is essentially the same idea.