This roadmap is produced based on Cats ecosystem community survey 2018 results.
A Cats 2.0 is released earlier in the year without any breaking changes on most modules except cats-laws and cats-testkit. We then start branching to allow the master branch to drop Scala 2.11 in Q2, but maintain a dedicated scala2_11 branch to continue support Scala 2.11 until near the end of 2019. During this period, we are going to backport incoming changes from master to the scala2_11 branch in a Scala 2.11 BC way. We will try to maintain as much as possible use site source compatibility between on Scala 2.11 code and Scala 2.12+ - but they will be source incompatible - mostly methods added to traits in 2.12 will only be available in 2.11 code in new XXXXBinCompatN traits. During this period, we'll release Cats on scala 2.12+ and 2.11 from two different branches.
The followings are the steps in each quarter.
Release 2.0: This is not the Cats 2.0 we’ve been discussing in the past. Most modules remain fully binary compatible with Cats 1.x on all Scala versions. The only breaking changes are:
- ScalaCheck 1.13, update to ScalaCheck 1.14
- breaking changes for Cats-laws
Start a Scala 2.11 dedicated branching scheme:
- Branch master - drops Scala 2.11, maintains is BC with 1.x
- Branch scala2_11 - Scala 2.11 code New changes to master have to be ported to branch scala2_11 in a 2.11 BC compatible way and try to maintain as use site source compatible as possible - e.g. a new type class method added to master is added to a syntax trait method in scala2_11 branch.
Note that 2.11 and 2.12+ code are NOT source compatible with each other, however, they will still maintain source compatibility with 2.0 and 1.x.