v2.8.0

Cats v2.8.0 is a binary-compatible release in the 2.x series. It is published for Scala 2.12, 2.13, and 3.1+ with Scala.js 1.8+ and Scala Native 0.4. This release is the first to support Scala 3 on the Native platform.

Features

• Add foldF to IorT by @isomarcte in #4075
• Add toIorT on EitherT by @isomarcte in #4108
• Add Order and PartialOrder For SortedMap by @isomarcte in #4092
• SemigroupK/MonoidK methods by @TimWSpence in #4084
• added ifF to Functor by @atais in #4146
• Alleycats: upgrade Iterable instance from Foldable to Traverse, add TraverseFilter by @bplommer in #4152
• Add Chain#knownSize and Chain#lengthCompare (sizeCompare) methods by @satorg in #4159
• Add missing Chain#distinctBy method by @satorg in #4156
• Move contain_ to UnorderedFoldable by @BalmungSan in #4183
• Added flatMapN by @domaspoliakas in #4009
• Add getOrRaise for OptionT, EitherT and IorT by @geirolz in #4212
• Support lifting polymorphic functions to FunctionK in Scala 3 by @bplommer in #3895
• Add mapAccumulate to Traverse by @BalmungSan in #4209
• Add replicateA_, parReplicateA_ by @rabinarai1 in #4208
• Cross-build for Scala 3 + Native by @armanbilge in #4228

Optimizations

• More efficient slidingN functions by @joroKr21 in #4067
• Optimize Chain length methods by @bplommer in #4166
• A few more Chain optimizations by @johnynek in #4170
• Optimise Kleisli with specialized Function1 implementation by @bplommer in #4211
• override more mapAccumulate methods in Traverse by @johnynek in #4214
• Optimize replicateA to have same recursive structure as replicateA_ by @johnynek in #4233
• Tail-recursive replicateA by @armanbilge in #4234

Fixes

• Add Semigroupal[Id] to implicit scope by @joroKr21 in #4056
• Remove @implicitNotFound annotations by @armanbilge in #4060
• Return stack-safe Function0 and Function1 from Semigroup#combine by @mrdziuban in #4093
• remove unused Apply#tupleN type param by @xuwei-k in #4142
• Make catsInstancesForIdCompat2_6_1 package-private by @armanbilge in #4191
• Make whenA/unlessA syntax by-name lazy by @catostrophe, @armanbilge in #4207
• weaken constraint on ParallelApOps and ParallelApplyOps methods by @jbwheatley in #4078
• Prevent Chain instances being backed by mutable or lazy Seq by @bplommer in #4169
• Use spurious Fractional[MiniInt] to test Invariant[Fractional] by @tmccarthy in #4216
• Expose newtype objects to Mima by @satorg in #4219

Deprecations

• Recommend Cats Effect IO as a replacement for every use case of Future by @BalmungSan, @johnynek, @armanbilge in #4230

  Any non-pure use of Future with Cats is error prone (particularly the semantics of traverse with regard to execution order are unspecified). We recommend using Cats Effect IO as a replacement for every use case of Future. However, at this time there are no plans to remove these instances from Cats.

  See also: #4176 Changes in Future traverse behavior between 2.6 and 2.7

Documentation

• Update maintainers by @rossabaker in #4073
• cats and category theory in readme by @SethTisue in #4090
• Add documentation for Bimonad by @gatear in #4076
• readme updates by @SethTisue in #4096
• Remove unused type parameter in Choice typeclass doc by @b-vennes in #4113
• DocTests for OptionT by @FelAl in #4038
• Documentation/update adopters & contibuting by @benkio in #4124
• Fix readme by @danicheg in #4141
• more doctests to Reducible by @dseer0 in #4148
• Minor typo by @lodamar in #4164
• Fix graphic in README by @armanbilge in #4174
• Add copyright notices and Scala license for code derived from the standard library by @DavidGregory084 in #4196
• adding all three Bartosz Milewski's parts for the Category Theory for Programmers course by @gokyo in #3992
• Readme: Remove references to old Scala versions by @bplommer in #4213
• Fix broken URLs in README.md by @maksymilianrozanski in #4218
• Make Bifoldable docs by @gatear in #4109
• StateT Documentation by @benkio in #4126

Adopters

• add lego and disney by @kailuowang in #4087
• Add iofod to users by @qkorbit in #4095
• Added OVO Energy to the list by @CoderDanUK in #4110
• add ClearScore to Adopters by @LydiaSkuse in #4155
• Prometeus -> Prometheus by @Marcus-Rosti in #4198
• Add Cognite to list of adopters by @hakontro in #4201
• Update README.md by @OnAirEntertainment-Scala in #4205
• Add Etsy as an adopter by @JasnaMRB in #4217

Behind-the-scenes

• Rm Jabba index by @danicheg in #4081
• Rename isDotty -> isScala3 by @armanbilge in #4119
• Clean up GenTupleParallelSyntax by @danicheg in #4127
• Reduce compilation warnings in tests by @satorg in #4083
• Migrate to sbt-typelevel by @armanbilge in #4160
• Build cleanups by @armanbilge in #4181
• temporarily disable tlFatalWarningsInCi by @satorg in #4186
• Add Scala Steward conf by @danicheg in #4197
• Remove unnecessary MiMa filters by @armanbilge in #4204
• Remove simulacrum by @BalmungSan in #4210
• Add new maintainers to developer list by @armanbilge in #4237

Updates

• Update scalafmt-core to 3.2.0 by @scala-steward in #4058
• Update sbt-github-actions to 0.14.0 by @scala-steward in #4064
• Update scalafmt-core to 3.2.1 by @scala-steward in #4069
• Update sbt-scalafmt to 2.4.5 by @scala-steward in #4071
• Update auxlib, javalib, nativelib, nscplugin, ... to 0.4.2 by @scala-steward in #4072
• Update discipline-core to 1.4.0 by @scala-steward in #4074
• Update sbt to 1.5.6 by @scala-steward in #4080
• Update sbt to 1.5.7 by @scala-steward in #4085
• Update snakeyaml to 1.30 by @scala-steward in #4086
• Update sbt to 1.5.8 by @scala-steward in #4091
• Update sbt-scalafmt to 2.4.6 by @scala-steward in #4098
• Update sbt to 1.6.0 by @scala-steward in #4099
• Update sbt to 1.6.1 by @scala-steward in #4100
• Update scalafmt-core to 3.3.0 by @satorg in #4101
• Update sbt-scalafix to 0.9.34 by @scala-steward in #4107
• Update scala-library, scala-reflect to 2.13.8 by @scala-steward in #4111
• Update auxlib, javalib, nativelib, nscplugin, ... to 0.4.3 by @scala-steward in #4115
• Update scalafmt-core to 3.3.3 by @scala-steward in #4116
• Update scalafmt-core to 3.4.0 by @scala-steward in #4121
• Update sbt to 1.6.2 by @scala-steward in #4122
• Update scalafmt-core to 3.4.2 by @scala-steward in #4129
• Update sbt-sonatype to 3.9.11 by @scala-steward in #4130
• Update scalafmt-core to 3.4.3 by @scala-steward in #4131
• Update sbt-buildinfo to 0.11.0 by @scala-steward in #4135
• Update sbt-sonatype to 3.9.12 by @scala-steward in #4136
• Update auxlib, javalib, nativelib, nscplugin, ... to 0.4.4 by @scala-steward in #4140
• Update sbt-scala-native-crossproject, ... to 1.2.0 by @scala-steward in #4150
• Update sbt-doctest to 0.10.0 by @scala-steward in #4151
• Update scalafmt-core to 3.5.0 by @scala-steward in #4157
• Update scalafmt-core to 3.5.1 by @scala-steward in #4163
• Update sbt-mima-plugin to 1.1.0 by @scala-steward in #4165
• Update fs2-core to 0.10.7 by @scala-steward in #4172
• Update scalaz-core to 7.2.34 by @scala-steward in #4173
• Update sbt-typelevel, sbt-typelevel-site to 0.4.9 by @scala-steward in #4180
• Update scalafmt-core to 3.5.2 by @scala-steward in #4192
• Update sbt-scalafix to 0.10.0 by @scala-steward in #4167
• Update scalaz-core to 7.3.6 by @scala-steward in #4179
• Update sbt-typelevel, sbt-typelevel-site to 0.4.10 by @typelevel-steward in #4226
• Update scalafmt-core to 3.5.8 by @typelevel-steward in #4223
• Update sbt-typelevel, sbt-typelevel-site to 0.4.11 by @typelevel-steward in #4227
• Update scala-library, scala-reflect to 2.12.16 by @typelevel-steward in #4231
• Update scala3-library, ... to 3.1.2 by @typelevel-steward in #4221
• Update sbt-typelevel, sbt-typelevel-site to 0.4.12 by @typelevel-steward in #4232
• Update sbt-scalajs, scalajs-compiler, ... to 1.10.0 by @typelevel-steward in #4220
• Update scalacheck to 1.16.0 by @typelevel-steward in #4222
• Update discipline-core to 1.5.1 by @typelevel-steward in #4225

Acknowledgements

A round of applause for the 38 contributors to this release, especially for keeping your PRs fresh while reviews were backlogged. We appreciate you so much!

And special thanks to the Cats' maintainers for their work on this release and especially their tireless, diligent PR reviews.

New Contributors

• @qkorbit made their first contribution in #4095
• @mrdziuban made their first contribution in #4093
• @CoderDanUK made their first contribution in #4110
• @b-vennes made their first contribution in #4113
• @FelAl made their first contribution in #4038
• @atais made their first contribution in #4146
• @dseer0 made their first contribution in #4148
• @LydiaSkuse made their first contribution in #4155
• @lodamar made their first contribution in #4164
• @Marcus-Rosti made their first contribution in #4198
• @hakontro made their first contribution in #4201
• @OnAirEntertainment-Scala made their first contribution in #4205
• @jbwheatley made their first contribution in #4078
• @geirolz made their first contribution in #4212
• @JasnaMRB made their first contribution in #4217
• @maksymilianrozanski made their first contribution in #4218
• @typelevel-steward made their first contribution in #4226
• @rabinarai1 made their first contribution in #4208

Full Changelog: v2.7.0...v2.8.0