v2.13.0

Cats v2.13.0 is a binary-compatible release in the 2.x series. It is published for Scala 2.12, 2.13, and 3.3 with Scala.js 1.17 and Scala Native 0.5.

What's Changed

The release comes with new APIs, as well as bugfixes and optimizations. While it is binary- and source- compatible, it is recommended for downstream projects to start replacing calls to sequence_ and traverse_ functions (along with their unordered* and par* counterparts) with sequenceVoid, traverseVoid, etc., correspondingly.

Features

• Add FunctionN.liftN, parLiftN by @kubukoz in #4340
• Add distinctBy to NonEmptyCollection and all impls by @cybersaurus in #4608
• Add Hash and Order Instances for NonEmptyVector by @isomarcte in #4612
• Semigroup object additions by @igstan in #4625
• Issue #4631: Make Later covariant by @yanns in #4632
• Add EitherOps#leftMapOrKeep and EitherOps#leftFlatMapOrKeep by @danicheg in #4638
• Add Defer.recursiveFn to aid in recursion by @johnynek in #4656
• Add unorderedFoldMapA method by @m50d in #4662
• alleycats - Extract[F[_]] the only way to get the syntax is the deprecated one by @aluscent in #4670
• Use alignWith in alignMergeWith by @joroKr21 in #4676
• Aliases traverseVoid/sequenceVoid and their counterparts by @satorg in #4682
• Add take/takeRight/drop/dropRight to Chain by @johnynek in #4694

Bugfixes

• Fix alleycats Set Functor ambiguous implicits by @LaurenceWarne in #4678

Optimizations

• Override Foldable#toIterable for Chain by @durban in #4693
• Optimize Chain.traverseVoid by @johnynek in #4695

Documentation

• add Blue Insight Digital to ADOPTERS.md by @ahoy196 in #4528
• correct & add documentation links by @performantdata in #4613
• Fix typo in Newtype scaladoc by @i-am-the-slime in #4619
• Fix broken internal link by @bwignall in #4622
• Point to sbt 1.x by @bwignall in #4624
• Fix typos by @bwignall in #4634
• Replace tut with mdoc on the colophon page by @danicheg in #4641
• Fix the broken link on the typeclasses page by @danicheg in #4645
• Fix foldLeft nomenclature signature by @Masynchin in #4648
• Fix some awkward imports by @satorg in #4659
• Fix Sponsors section by @valencik in #4660
• Change IPONWEB to Criteo in ADOPTERS.md by @bio-aeon in #4679

Behind-the-scenes

• Use helper functions in generated code by @joroKr21 in #4303
• Fix/suppress warnings in kernel and kernel-laws by @satorg in #4614
• Adjust the JVM options to heal the Native build on CI by @danicheg in #4623
• Rename root -> cats in build.sbt by @danicheg in #4644
• use & instead of with by @xuwei-k in #4673

Updates

• Update GraalVM from 17 to 21 by @mzuehlke in #4667
• Update auxlib, clib, javalib, nativelib, ... to 0.5.2 by @typelevel-steward in #4607
• Update auxlib, clib, javalib, nativelib, ... to 0.5.3 by @typelevel-steward in #4609
• Update auxlib, clib, javalib, nativelib, ... to 0.5.4 by @typelevel-steward in #4627
• Update auxlib, clib, javalib, nativelib, ... to 0.5.5 by @typelevel-steward in #4646
• Update auxlib, clib, javalib, nativelib, ... to 0.5.6 by @typelevel-steward in #4675
• Update munit to 1.0.1 by @typelevel-steward in #4643
• Update munit to 1.0.2 by @typelevel-steward in #4653
• Update munit to 1.0.3 by @typelevel-steward in #4684
• Update munit to 1.0.4 by @typelevel-steward in #4697
• Update sbt to 1.10.1 by @typelevel-steward in #4633
• Update sbt to 1.10.2 by @typelevel-steward in #4655
• Update sbt to 1.10.3 by @typelevel-steward in #4666
• Update sbt to 1.10.4 by @typelevel-steward in #4669
• Update sbt to 1.10.5 by @typelevel-steward in #4672
• Update sbt, scripted-plugin to 1.10.6 by @typelevel-steward in #4683
• Update sbt, scripted-plugin to 1.10.7 by @typelevel-steward in #4691
• Update sbt-buildinfo to 0.13.0 by @typelevel-steward in #4671
• Update sbt-buildinfo to 0.13.1 by @typelevel-steward in #4674
• Update sbt-doctest to 0.11.0 by @typelevel-steward in #4668
• Update sbt-doctest to 0.11.1 by @typelevel-steward in #4688
• Update sbt-scalajs, scalajs-compiler, ... to 1.17.0 by @typelevel-steward in #4685
• Update sbt-typelevel, sbt-typelevel-site to 0.7.2 by @typelevel-steward in #4636
• Update sbt-typelevel, sbt-typelevel-site to 0.7.3 by @typelevel-steward in #4651
• Update sbt-typelevel, sbt-typelevel-site to 0.7.4 by @typelevel-steward in #4665
• Update sbt-typelevel, sbt-typelevel-site to 0.7.5 by @typelevel-steward in #4692
• Update sbt-typelevel, sbt-typelevel-site to 0.7.6 by @typelevel-steward in #4701
• Update scala-library, scala-reflect to 2.12.20 by @typelevel-steward in #4649
• Update scala-library, scala-reflect to 2.13.15 by @typelevel-steward in #4657
• Update scala-library, scala-reflect to 2.13.16 by @typelevel-steward in #4699
• Update scala3-library, ... to 3.3.4 by @typelevel-steward in #4658
• Update scalacheck to 1.18.1 by @typelevel-steward in #4654
• Update scalafmt-core to 3.8.2 by @typelevel-steward in #4620
• Update scalafmt-core to 3.8.4 by @typelevel-steward in #4698
• Update scalafmt-core to 3.8.5 by @typelevel-steward in #4700

New Contributors

• @cybersaurus made their first contribution in #4608
• @performantdata made their first contribution in #4613
• @i-am-the-slime made their first contribution in #4619
• @yanns made their first contribution in #4632
• @mzuehlke made their first contribution in #4667
• @ahoy196 made their first contribution in #4528
• @LaurenceWarne made their first contribution in #4678
• @aluscent made their first contribution in #4670

Full Changelog: v2.12.0...v2.13.0

v2.12.0

Cats v2.12.0 is a binary-compatible release in the 2.x series. It is published for Scala 2.12, 2.13, and 3.3+ with Scala.js 1.13+ and Scala Native 0.5.

What's Changed

Features

• Add flatMapOrKeep to Monad by @jozic in #4602

Behind-the-Scenes

• Remove special ExecutionContextExecutor by @kapunga in #4601
• Bump base version to 2.12 by @mpilquist in #4606

Updates

• Update nscplugin, sbt-scala-native to 0.5.1 by @typelevel-steward in #4585
• Update discipline-munit to 2.0.0 by @typelevel-steward in #4605

New Contributors

• @kapunga made their first contribution in #4601

Full Changelog: v2.11.0...v2.12.0

v2.11.0

Cats v2.11.0 is a binary-compatible release in the 2.x series. It is published for Scala 2.12, 2.13, and 3.3+ with Scala.js 1.13+ and Scala Native 0.4.

What's Changed

Features

• Add OptionT#unlessM by @m50d in #4519
• Add mapOrKeep to Functor by @jozic in #4582
• Expose FunctionK.liftFunction as a part of the Scala 3 API by @pomadchin in #4600
• FunctionKLift cross compiled liftFunction suite by @pomadchin in #4603

Optimizations

• Replaces other Applicative.pure(()) with .unit by @satorg in #4558
• Use Applicative#unit in Foldable#traverse_ by @valencik in #4557
• Optimize traverse by @TimWSpence in #4498

Fixes

• Fix EitherT Bifunctor priority, add Bifoldable instance by @joroKr21 in #4576
• fix ambiguous ContravariantShow[SortedSet[A]] (& SortedMap) by @chwthewke in #4575
• Reduce visibility of value member in the NonEmptyMap syntax by @TonioGela in #4559

Documentation

• Fix link to Fetch by @mainali123 in #4522
• update book's link to second edition by @naferx in #4524
• fix wording at end of Semigroup doc by @vreuter in #4551
• Fix choice alias render in docs by @Masynchin in #4580
• fix typo by @Ghurtchu in #4583
• Use syntax in Functor's doc examples by @jozic in #4599

Behind-the-scenes

• fix MonadOps.scala and FunctionKMacros.scala dir by @xuwei-k in #4548
• Bump base version to 2.11 by @armanbilge in #4496
• add explicit type by @xuwei-k in #4508
• fix warning in build.sbt by @xuwei-k in #4518
• enforce new wildcard syntax by @xuwei-k in #4544
• Update copyright date by @geny200 in #4593

Updates

• Update sbt-typelevel, sbt-typelevel-site to 0.5.0 by @typelevel-steward in #4497
• Update sbt to 1.9.4 by @typelevel-steward in #4500
• Update scalafmt-core to 3.7.13 by @typelevel-steward in #4502
• Update scalafmt-core to 3.7.14 by @typelevel-steward in #4503
• Update sbt-jmh to 0.4.6 by @typelevel-steward in #4506
• Update scala3-library, ... to 3.3.1 by @typelevel-steward in #4507
• Update nscplugin, sbt-scala-native, ... to 0.4.15 by @typelevel-steward in #4505
• Update sbt-typelevel, sbt-typelevel-site to 0.5.1 by @typelevel-steward in #4509
• Update scala-library, scala-reflect to 2.13.12 by @typelevel-steward in #4510
• Update sbt-typelevel, sbt-typelevel-site to 0.5.2 by @typelevel-steward in #4511
• Update sbt to 1.9.5 by @typelevel-steward in #4512
• Update munit to 1.0.0-M9 by @typelevel-steward in #4513
• Update sbt to 1.9.6 by @typelevel-steward in #4515
• Update sbt-typelevel, sbt-typelevel-site to 0.5.3 by @typelevel-steward in #4517
• Update munit to 1.0.0-M10 by @typelevel-steward in #4516
• Update sbt-scalajs, scalajs-compiler, ... to 1.14.0 by @typelevel-steward in #4520
• Update sbt-typelevel, sbt-typelevel-site to 0.5.4 by @typelevel-steward in #4523
• Update flatMapF in nomenclature.md by @pera in #4525
• Update nscplugin, sbt-scala-native, ... to 0.4.16 by @typelevel-steward in #4526
• Update sbt-typelevel, sbt-typelevel-site to 0.6.0 by @typelevel-steward in #4527
• Update sbt to 1.9.7 by @typelevel-steward in #4529
• Update scalafmt-core to 3.7.15 by @typelevel-steward in #4530
• Update sbt-typelevel, sbt-typelevel-site to 0.6.1 by @typelevel-steward in #4532
• Update sbt-typelevel, sbt-typelevel-site to 0.6.2 by @typelevel-steward in #4535
• Update scalafmt-core to 3.7.17 by @typelevel-steward in #4536
• Update sbt-typelevel, sbt-typelevel-site to 0.6.3 by @typelevel-steward in #4538
• Update sbt-jmh to 0.4.7 by @typelevel-steward in #4539
• Update sbt to 1.9.8 by @typelevel-steward in #4541
• Update sbt-typelevel, sbt-typelevel-site to 0.6.4 by @typelevel-steward in #4542
• Update sbt-typelevel, sbt-typelevel-site to 0.6.5 by @typelevel-steward in #4546
• Update nscplugin, sbt-scala-native, ... to 0.4.17 by @typelevel-steward in #4550
• Update sbt-scalajs, scalajs-compiler, ... to 1.15.0 by @typelevel-steward in #4549
• Update munit to 1.0.0-M11 by @typelevel-steward in #4556
• Update sbt-typelevel, sbt-typelevel-site to 0.6.6 by @typelevel-steward in #4560
• Update scalafmt-core to 3.8.0 by @typelevel-steward in #4563
• Update sbt to 1.9.9 by @typelevel-steward in #4565
• Update sbt-typelevel, sbt-typelevel-site to 0.6.7 by @typelevel-steward in #4566
• Update scala-library, scala-reflect to 2.13.13 by @typelevel-steward in #4568
• Update scala-library, scala-reflect to 2.12.19 by @typelevel-steward in #4567
• Update scala3-library, ... to 3.3.3 by @typelevel-steward in #4571
• Update sbt-buildinfo to 0.12.0 by @typelevel-steward in #4577
• Update scalafmt-core to 3.8.1 by @typelevel-steward in #4578
• Update sbt-scalajs, scalajs-compiler, ... to 1.16.0 by @typelevel-steward in #4581
• Update discipline-core to 1.6.0 by @typelevel-steward in #4588
• Update scalacheck to 1.17.1 by @typelevel-steward in #4586
• Update sbt-typelevel, sbt-typelevel-site to 0.7.0 by @typelevel-steward in #4591
• Update munit to 1.0.0-RC1 by @typelevel-steward in #4592
• Update scala-library, scala-reflect to 2.13.14 by @typelevel-steward in #4594
• Update sbt to 1.10.0 by @typelevel-steward in #4596
• Update sbt-typelevel, sbt-typelevel-site to 0.7.1 by @typelevel-steward in #4597
• Update munit to 1.0.0 by @typelevel-steward in #4604

New Contributors

• @m50d made their first contribution in #4519
• @mainali123 made their first contribution in #4522
• @naferx made their first contribution in #4524
• @vreuter made their first contribution in #4551
• @chwthewke made their first contribution in #4575
• @Ghurtchu made their first contribution in #4583
• @geny200 made their first contribution in #4593
• @pomadchin made their first contribution in #4600

Full Changelog: v2.10.0...v2.11.0

v2.10.0

Cats v2.10.0 is a binary-compatible release in the 2.x series. It is published for Scala 2.12, 2.13, and 3.3+ with Scala.js 1.13+ and Scala Native 0.4.

This release includes #4477 which fixes the encoding of Apply (and Semigroupal) syntax to avoid allocating an intermediate "Ops" wrapper class. This affected commonly-used operators such as *>. Unfortunately libraries will need to re-compile and re-publish against Cats v2.10.0 to use the new allocation-free syntax.

Thanks to all the contributors to this release! There are many accumulated changes.

What's Changed

Features

• Add OptionT combinators for effectful Boolean by @ivan-klass in #4390
• Add Bifunctor#leftLiftTo by @eugkhp in #4336
• Add Kleisli.localK FunctionK helper by @ivan-klass in #4406
• add zip for NonEmptySeq by @CristinaHG in #4431
• Add Functor#composeBifunctor by @bpholt, @armanbilge in #4434
• Add Validated.unit by @VladKopanev in #4420
• Add raiseWhen/raiseUnless convenience methods to EitherObjectOps by @Daenyth in #4436
• OneAnd: add PartialOrder and Order instances by @satorg in #4460
• Add Defer instances for Eq, Hash, Order, Show, and variants by @morgen-peschke in #4414
• Fix ambiguous Const instances and add missing instances by @joroKr21 in #4458

Optimizations

• Avoid allocating an Option in NonEmptyList#last by @valencik in #4417
• Improve foldRight for Seq instance by @rudolmi in #4440

Fixes

• Move catsTraverseForSeq to lower-priority implicit scope by @UlisesTorrella in #4373
• Making Map.unorderedTraverse stack safe by @TonioGela in #4463
• Fix unnecessary syntax allocation by @mox692 in #4477

Documentation

• Nomenclature for the SemigroupK hierarchy by @TimWSpence in #4329
• Fix readme by @danicheg in #4368
• Fix the nested unordered list HTML view of docs/typeclasses/alternative.md by @ShapelessCat in #4371
• Fix typo by @Masynchin in #4381
• Add missing syntax highlightning by @Masynchin in #4382
• Add a link about fs2-throttler by @kovstas in #4359
• Publish alleycats docs on website by @armanbilge in #4393
• cats.implicits._ -> cats.syntax.all._ by @armanbilge in #4394
• Update no script links in readme by @RawToast in #4397
• Update CONTRIBUTING.md microsite information by @fabianhjr in #4399
• Improve Chain Documentation by @reardonj in #4386
• Add API documentation links by @reardonj in #4401
• f >>> g in symbols table by @jose-puente in #4411
• Fix outdated edit link in algebra docs by @lenguyenthanh in #4418
• Update version in readme by @lenguyenthanh in #4422
• Fix typo in Ior docs by @fighur in #4423
• Update Ring-like table in Algebra for Semifield added in #3979 by @benhutchison in #4426
• Add foldr note to Foldable doc by @lenguyenthanh in #4425
• Bump versions in law testing doc by @lenguyenthanh in #4424
• ExhaustiveCheck is a list, not a stream by @rossabaker in #4442
• Fix traverseWithIndex => traverseWithIndexM by @lenguyenthanh in #4443
• Fix typo in core's package object docs by @fatalem0 in #4446
• Fix jump_start_guide.md typo by @BokChoyWarrior in #4465
• Remove Either documentation page by @reardonj in #4400
• Add doctest for IdT by @bulatkhabib in #4445
• Fix typo by @bwignall in #4482

Adopters

• Add IPONWEB as an adopter by @bio-aeon in #4384
• Update ADOPTERS.md by @ehsun7b in #4435
• Add PITS Globale Datenrettungsdienste as an adopter by @arnoldberlin in #4472

Behind-the-scenes

• Bump base version to 2.10 by @armanbilge in #4341
• Remove plugins we get via sbt-typelevel by @armanbilge in #4344
• Clean up benchmarks' dependencies by @danicheg in #4355
• Fix Native CI by @armanbilge in #4363
• remove unused version number by @kailuowang in #4358
• Move NonEmptyReducible into its own file by @fabianhjr in #4398
• Delete PR template by @joroKr21 in #4459
• Replaced traverse benchmarks with something more representative by @djspiewak in #4403
• Update to sbt-typelevel 0.5.0 by @armanbilge in #4478

Updates

• Update scala3-library, ... to 3.3.0 by @typelevel-steward in #4448
• Update nscplugin, sbt-scala-native, ... to 0.4.14 by @typelevel-steward in #4454
• Update scala-library, scala-reflect to 2.12.18 by @typelevel-steward in #4455
• Update scala-library, scala-reflect to 2.13.11 by @typelevel-steward in #4456
• Update sbt-scalajs, scalajs-compiler, ... to 1.13.2 by @typelevel-steward in #4464

New Contributors

• @ShapelessCat made their first contribution in #4371
• @UlisesTorrella made their first contribution in #4373
• @Masynchin made their first contribution in #4381
• @bio-aeon made their first contribution in #4384
• @kovstas made their first contribution in #4359
• @fabianhjr made their first contribution in #4398
• @reardonj made their first contribution in #4386
• @eugkhp made their first contribution in #4336
• @jose-puente made their first contribution in #4411
• @lenguyenthanh made their first contribution in #4418
• @fighur made their first contribution in #4423
• @ehsun7b made their first contribution in #4435
• @CristinaHG made their first contribution in #4431
• @VladKopanev made their first contribution in #4420
• @rudolmi made their first contribution in #4440
• @fatalem0 made their first contribution in #4446
• @BokChoyWarrior made their first contribution in #4465
• @arnoldberlin made their first contribution in #4472
• @bulatkhabib made their first contribution in #4445
• @mox692 made their first contribution in #4477

Full Changelog: v2.9.0...v2.10.0

v2.9.0

Cats v2.9.0 is a binary-compatible release in the 2.x series. It is published for Scala 2.12, 2.13, and 3.2+ with Scala.js 1.8+ and Scala Native 0.4.

What's Changed

Features

• Added updated to Traverse by @nikololiahim in #4248
• Added zipWithLongIndex, mapWithLongIndex and traverseWithLongIndexM by @nikololiahim in #4247
• Add collectFirst to the NonEmptyCollection interface by @DavidGregory084 in #4275
• Added discipline tests for the new Traverse laws by @nikololiahim in #4283
• Add traverseCollect to TraverseFilter typeclass by @emilhotkowski in #4277
• Add NonEmptyList#prependAll by @saeltz in #4267
• Add EitherT#biSemiflatTap which combines leftSemiflatTap and semiflatTap by @exp0nge in #4293
• Optimize Alternative (part 3): add prependK/appendK specializations for Cats NE wrappers by @satorg in #4055
• Added parFlatMapN by @TonioGela in #4243
• Added Align instances for Id and Kleisli by @atnoya in #4287
• Add ApplicativeError#voidError by @armanbilge in #4324

Optimizations

• Change the ordering of invocations in Defer#fix by @TimWSpence in #4252
• Optimise boilerplate generators, use instance constructors by @joroKr21 in #3871
• Avoid using NonFatal.unapply by @jhnsmth in #4282
• Use SAM syntax for typeclass instances where possible by @joroKr21 in #4279
• Singleton monoid instances by @TimWSpence in #4314
• Avoid allocations for Monoid instances where possible by @bplommer in #4309
• Make string building a bit more efficient for NonEmptySeq by @danicheg in #4326

Fixes

• Don't require Order for the value on Cogen for SortedMap and NonEmptyMap by @cquiroz in #4296
• Make cats.compat a package object for for2_13Use3 compatibility by @TonioGela in #4315
• Fix ambiguous contains_ syntax by @armanbilge in #4320

Deprecations

• Deprecate HashLaws#sameAsUniversalHash by @armanbilge in #4319

Documentation

• Remove LEGO from adopters list by @hejfelix in #4242
• Fix Free Monad example by @youta32449999 in #4253
• Mention asRight and asLeft for constructing Either values by @benhutchison in #4257
• Fix comment in Free Monad example by @youta32449999 in #4259
• Add proof of inconsistency for a Validated Monad by @TonioGela in #4255
• Mention tupled syntax, a Cats workhorse that deserves to be more well known by @benhutchison in #4269
• Add missing scala modifier to code block by @armanbilge in #4274
• Build docs on 2.13 by @armanbilge in #4238
• Fix list formatting in docs / site by @valencik in #4290
• Move the adopters' companies list to a separate file/page by @danicheg in #4291
• Keep the cats version up to date on the website by @danicheg in #4294
• Include laws in published API docs by @armanbilge in #4318
• Fix markdown syntax for link to Applicative in OptionT by @yoshinorin in #4321
• Add more DocTests for OptionT by @timo-schmid in #4311

Behind-the-scenes

• Ignore updates to cats-core by @armanbilge in #4241
• Bump base version to 2.9 by @armanbilge in #4239
• Refactored Chain and CollectiveMonoid benchmarks by @TonioGela in #4264
• Fix obvious and straightforward warnings by @satorg in #4323
• Add commits to .git-blame-ignore-revs by @armanbilge in #4334
• Add stack-safety test for ContT#map by @eigenvariable in #4335
• Add release notes config by @armanbilge in #4330

Updates

• Update sbt-scalajs, scalajs-compiler, ... to 1.10.1 by @typelevel-steward in #4254
• Update nscplugin, sbt-scala-native, ... to 0.4.7 by @typelevel-steward in #4289
• Update scalacheck to 1.17.0 by @typelevel-steward in #4297
• Update scala3-library, ... to 3.2.1 by @typelevel-steward in #4337

New Contributors

• @hejfelix made their first contribution in #4242
• @youta32449999 made their first contribution in #4253
• @nikololiahim made their first contribution in #4248
• @TonioGela made their first contribution in #4255
• @emilhotkowski made their first contribution in #4277
• @valencik made their first contribution in #4290
• @exp0nge made their first contribution in #4293
• @cquiroz made their first contribution in #4296
• @atnoya made their first contribution in #4287
• @yoshinorin made their first contribution in #4321
• @eigenvariable made their first contribution in #4335
• @timo-schmid made their first contribution in #4311

Full Changelog: v2.8.0...v2.9.0

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...

Cats 2.7.0

The most significant change in this release is the incorporation of the Typelevel Algebra project within Cats. Cats has long been the primary downstream dependent of this library, and it has significant overlap with a lot of the Cats core mission. Note that this change was made without breaking binary compatibility for transitive downstream users of Algebra, meaning that the package remains algebra rather than the more-conventional cats.algebra. This will be adjusted in Cats 3, which has no timeline at present.

Additions

• #4052 Optimize Alternative (part 2): add prependK/appendK specializations for std containers by @satorg
• #4014 optimize Alternative (part 1): introduce NonEmptyAlternative with prependK and appendK methods by @satorg
• #3931 Add missing methods to VectorOps by @satorg
• #4036 Adding Id.apply by @BalmungSan
• #4032 Invariant[Fractional] by @tmccarthy
• #4029 Add parReduceMapA by @isomarcte
• #4007 Introduce parReplicateA by @RafalSumislawski
• #4015 Implement OptionT#foreachF by @armanbilge
• #3979 Add Semifield and CommutativeSemifield to algebra by @armanbilge
• #3963 NonEmptyMap: add new methods by @satorg
• #3987 Implement InvariantCoyoneda by @armanbilge

Changes

• #3997 Relax a constraint for Alternative's unite and separate methods from Monad to FlatMap by @satorg
• #4044 Incorrect deprecated messages by @jmgimeno
• #4046 Add missing else keyword to example by @Steve
• #4040 Add Adobe CCA team as users of Cats by @gatear
• #4039 Remove out-of-date comment by @TimWSpence
• #4037 Typo fix: ',' instead of '=>' by @JakubSzczerbinski
• #4026 Using cats.syntax.all instead of cats.implicits in the docs by @BalmungSan
• #4024 Add library Jms4s to the ecosystem page by @benkio
• #4017 Adding Medidata as an Adopter in the README.md by @tmilner
• #4013 Add SEEK Limited to Adopter list by @bjing
• #4005 Typelevel ecosystem broken links fix by @benkio
• #3944 add identity hash to alleycats by @SimY4
• #3985 Add NetworkedAssets to adopters list by @RafalSumislawski
• #3984 Use OpenCollective GraphQL API to render sponsors by @armanbilge
• #3918 Binary-compatibly move typelevel/algebra into cats repo by @armanbilge
• #3972 Render sponsors from Open Collective REST API by @rossabaker
• #3967 override toIterable more and use it by @johnynek
• #3960 Fix traverse_ for List and Vector to be stack safe by @johnynek
• #3949 Added implementation of Eq[Free] by @djspiewak
• #3956 Configure microsite image directory by @rossabaker
• #3958 Eq[NonEmptySet[A]] now needs Eq[A], not Order[A] by @domaspoliakas
• #3945 Cleanup ScalaStyle things by @danicheg
• #3951 Override map2Eval in FlatMap by @vasilmkd
• #3943 Use new sbt syntax for fmt commands by @danicheg
• #3932 Add Tranzzo to adopters list by @gorbylov
• #3894 Test FunctionK in scala 3 by @bplommer
• #3893 Deprecate ifA by @diesalbla
• #3909 Add doctests to Bifoldable by @brs96
• #3906 Move Id instances into implicit scope for Scala 3 by @joroKr21

Cats 2.6.1

There are no noteworthy additions in this release, but it is the first Cats release for Scala 3!

Cats 2.6.0

Cats 2.6.0 is a binary-compatible release in the 2.x series. It provides support for Scala 2.12, 2.13, 3.0.0-RC2 and 3.0.0-RC3.

Additions

• #3831 Add composition to Representable by @TimWSpence
• #3832 Representable instance for Tuple2K by @TimWSpence
• #3837 Provide instance of Alternative[Set] in alleycats by @rtyley
• #3836 RepresentableStoreT by @TimWSpence

Changes

• #3847 Make deprecated catsDataInstancesForNonEmptyMap not implicit by @joroKr21 (source breaking)
• #3720, #3852 fix show interpolation ambiguity with Seq/List by @tnielens
• #2254, #3856 Remove redundant Monad constraints from Parallel syntax by @joroKr21
• #3851 Update 'Jump Start Guide' page to modern cats by @chaitanyawaikar

Cats 2.5.0

Cats 2.5.0 is a binary-compatible release in the 2.x series. It provides support for Scala 2.12, 2.13, 3.0.0-RC1 and 3.0.0-RC2.

Additions

• #3808 Chain add fromOption factory method by @nikiforo
• #3826, #3827 Add syntax for parProduct and parAp by @nigredo-tori
• #3804, #3805 Add Ior.mergeWith and AlignMergeWith by @nigredo-tori
• #3806 Add Align instance for Nested by @nigredo-tori
• #3643, #3823 Add sumAll & productAll by @phongngtuan, @larsrh

Changes

• #3818 update Scala to 2.13.5 by @sh0hei
• #3825 Use -scalajs-mapSourceURI in Scala 3 builds by @fthomas
• #3377, #3807 Replace Band instance for NonEmptyMap with a Semigroup instance consistent with SortedMap by @nigredo-tori
• #3480, #3833 Rename master to main by @travisbrown, @larsrh

Documentation

• #3814 typo in ApplicativeError by @wibisono