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Version: 1.0.18


Task[A] is a type alias for ZIO[Any, Throwable, A], which represents an effect that has no requirements, and may fail with a Throwable value, or succeed with an A.

Let's see how the Task type alias is defined:

type Task[+A] = ZIO[Any, Throwable, A]

So the Task just equal to ZIO which doesn't require any dependency. Its error channel is Throwable, so it may fail with Throwable and may succeed with an A value.


In Scala, the type alias is a way to give a name to another type, to avoid having to repeat the original type again and again. It doesn't affect the type-checking process. It just helps us to have an expressive API design.

Some time, we know that our effect may fail, but we don't care the type of that exception, this is where we can use Task. The type signature of this type-alias is similar to the Future[T] and Cats IO.

If we want to be less precise and want to eliminate the need to think about requirements and error types, we can use Task. This type-alias is a good start point for anyone who wants to refactor the current code base which is written in Cats IO or Monix Task.

Note: Principle of The Least Power

The ZIO data type is the most powerful effect in the ZIO library. It helps us to model various types of workflows. On other hand, the type aliases are a way of subtyping and specializing the ZIO type, specific for a less powerful workflow.

Lot of the time, we don't need such a piece of powerful machinery. So as a rule of thumb, whenever we require a less powerful effect, it's better to use the proper specialized type alias.

So there is no need to convert type aliases to the ZIO data type, whenever the ZIO data type is required, we can use the most precise type alias to fit our workflow requirement.