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Update the outdated FAQ on IO/Task #2337

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Jul 26, 2018
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Update the outdated FAQ on IO/Task #2337

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2 changes: 1 addition & 1 deletion docs/src/main/tut/faq.md
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Expand Up @@ -129,7 +129,7 @@ In purely functional programming, a monadic `IO` or `Task` type is often used to

The answer is that cats *does* include an `IO`, it just isn't included in the core library. The decision was made to split `IO` away from cats-core and (indeed the whole cats release cycle!) in order to make it easier to ensure modular versioning and compatibility across the ecosystem. The [cats-effect](https://github.com/typelevel/cats-effect) project defines a type, `cats.effect.IO`, which is intended to be a very minimal, very performant data type for managing synchronous and asynchronous side-effects, integrated into the cats ecosystem.

However, we acknowledge that this type may not meet everyone's needs. Notably, `cats.effect.IO` does not provide any mechanism for achieving parallel computation (though such functionality can be built on top of it, which is what libraries like [fs2](https://github.com/functional-streams-for-scala/fs2) achieve). For these and other needs, we would invite you to consider one of the other `Task`-like data types within the cats ecosystem, such as [Monix's `Task`](https://monix.io). The cats-effect project characterizes the space of side-effect-capturing data types with a set of typeclasses (deriving from `cats.Monad`), and so all such data types are, broadly-speaking, mutually compatible and interchangeable in many generic contexts.
However, we acknowledge that this type may not meet everyone's needs. The cats-effect project characterizes the space of side-effect-capturing data types with a set of typeclasses (deriving from `cats.Monad`), and so all such data types are, broadly-speaking, mutually compatible and interchangeable in many generic contexts. For example, [Monix](https://monix.io) provides support for IO, concurrency, and streaming and integrates with the cats-effect type classes.

It may be worth keeping in mind that `IO` and `Task` are pretty blunt instruments (they are essentially the `Any` of side effect management), and you may want to narrow the scope of your effects throughout most of your application. The [free monad]({{ site.baseurl }}/datatypes/freemonad.html) documentation describes a way to abstractly define controlled effects and interpret them into a type such as `IO` or `Task` as late as possible. As more of your code becomes pure through these controlled effects the less it matters which type you end up choosing to represent your side effects.

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