Add the Empty[Option[A]] instance in alleycats #4733
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alleycats-core/src/main/scala-2.13+/alleycats/compat/IterableEmptyInstance.scala
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It turns out that an instance of
alleycats.Empty[Option[A]]isn't automatically derived if there is noSemigroupinstance forAin scope. See the example: https://scastie.scala-lang.org/gndrZPa1QA6deeYzhNhvQw. Interestingly, adding an import ofalleycats.std.optiondoesn't help either.