This is the second release candidate for Cats 2.2.0. We decided to publish another release candidate because of several significant implementation improvements by @johnynek, including in particular #3519 and #3521. This release is verified to be backward binary compatible with 2.2.0-RC1, 2.2.0-M3, and all 2.1.x and 2.0.x releases (and also with 1.x for the non-laws modules), but not with 2.2.0-M1 or 2.2.0-M2.

7 API / feature enhancements

• #3524 A method StateT.fromState turning State[A, F[B]] into StateT[F,A, B] is added. by @akopich
• #3498 Enable breakout in functions reduceRightToOption and reduceRightTo. by @takayahilton
• #3519 remove casts from Eval, fix stack overflow in Eval by @johnynek
• #3521 make collection traversals stack safe by @johnynek
• #3516 Override some Option Apply/Applicative methods by @johnynek
• #3518 remove some casts in AndThen by @johnynek
• #3515 Add some more implementations to Function0 and Function1 Monads by @johnynek

3 build improvements

• #3525 Update scalafmt-core to 2.6.4 by @scala-steward
• #3520 Update sbt-scalafix to 0.9.19 by @scala-steward
• #3514 Scalafmt-core 2.6.3 by @barambani