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Interesting. What language is a good example of having effect sets? Koka? What about the case of needing context like “correlation id,” from the article? Ca

• isaacimagine 5y ago
  Koka is a good example of a language having effect sets: in koka, it's called a row of effects, and is written as <exn, console, e> where single letters denote generic params. In the case of needing a correlation id, this is a great use case for effects! First we declare an effect type: effect correlation_id ctl id(): int Then we set up a handler: with ctl id() resume(7) log("nice!") Here we just use 7, but we could be incrementing a counter per request or something. Then any functions that are called in this scope, when they call 'id', will receive 7: fun log(message: string): <console, correlation_id> () { println(id()) println(message) } Which, using the above handler, would print: 7 nice! For example. Hope this helps!