catcheffect

An abstraction that can construct an instance of the Handle mtl algebra without any constraints.

Catch provides the (cap)ability to introduce ad-hoc error channels which compose, like cats.data.EitherT, but with no required lifting (and un-lifting).

Catch, unlike mtl stacks, Catch does not require introuction of more monad transformers when layering.

Nested handlers for Catch are well-defined.

An abstraction that can construct an instance of the Local mtl algebra without any constraints.

You gain the (cap)ability to introduce a new instance of Local for any type, anywhere a Context is present.

For programs written in cats.data.Kleisli or tagless final, Context provides the ability to introduce new Local instances without having to lift any algebras or penalize your performance.

Nested use of Context is well defined.