0.2.19.1

• Fix bug in intersection[With[Key]]

• Improve docs of bit twiddling functions

0.2.19.0

• Make intersections much faster

• Fix undefined behaviour on 32-bit platforms

• Speed up some array-appending operations: #407, #409

• Use MathJax format for complexity annotations

0.2.18.0

• Fix strictness properties of Strict.mapMaybe[WithKey]

• Fix strictness properties of Strict.alterFEager

• Fix space leaks in union[With[Key]]

• Fix space leak in Lazy.fromListWith

• Speed up difference* and intersection* with unsafeInsert

• unionArrayBy: Find next 1-bits with countTrailingZeros

  • This speeds up union* for sparsely filled nodes, while penalizing union operations on densely filled nodes.

• Reduce reboxing in internal array operations

• Reduce code size of array operations in union*

0.2.17.0

• Define dataCast1 for HashMap

• Add Lift instances for Template Haskell

• Add definitions for stimes

• Expose internal constructors for HashSet, Array and MArray

• Tweak internal Array.insertM function

• Drop support for GHC 8.0

• Drop support for hashable < 1.2.5

• Various cleanup and documentation improvements

0.2.16.0

• Increase maximum branching factor from 16 to 32

• Tweak union.goDifferentHash

• Fix debug mode bounds check in cloneM

• Remove some old internal compatibility code

0.2.15.0

• Add security advisory regarding hash collision attacks

• Add support for hashable 1.4

• Drop support for GHC < 8

0.2.14.0

• Add HashMap.mapKeys. Thanks, Marco Perone!

• Add instances for NFData1 and NFData2. Thanks, Isaac Elliott and Oleg Grenrus!

• Fix @since-annotation for compose. Thanks, @Mathnerd314!

0.2.13.0

• Add HashMap.compose. Thanks Alexandre Esteves.

0.2.12.0

• Add HashMap.isSubmapOf[By] and HashSet.isSubsetOf. Thanks Sven Keidel. (#282)

• Expose internal modules. (#283)

• Documentation improvements in Data.HashSet, including a beginner-friendly
  introduction. Thanks Matt Renaud. (#267)

• HashMap.alterF: Skip key deletion for absent keys. (#288)

• Remove custom unsafeShift{L,R} definitions. (#281)

• Various other documentation improvements.

0.2.11.0

• Add HashMap.findWithDefault (soft-deprecates HashMap.lookupDefault).
  Thanks, Matt Renaud.

• Add HashMap.fromListWithKey. Thanks, Josef Svenningsson.

• Add more folding functions and use them in Foldable instances. Thanks,
  David Feuer.

• Add HashMap.!?, a flipped version of lookup. Thanks, Matt Renaud.

• Add a Bifoldable instance for HashMap. Thanks, Joseph Sible.

• Add a HasCallStack constraint to (!). Thanks, Roman Cheplyaka.

Bug fixes

• Fix a space leak affecting updates on keys with hash collisions. Thanks,
  Neil Mitchell. (#254)

• Get rid of some silly thunks that could be left lying around. (#232).
  Thanks, David Feuer.

Other changes

• Speed up the Hashable instances for HashMap and HashSet. Thanks,
  Edward Amsden.

• Remove a dependency cycle hack from the benchmark suite. Thanks,
  Andrew Martin.

• Improve documentation. Thanks, Tristan McLeay, Li-yao Xia, Gareth Smith,
  Simon Jakobi, Sergey Vinokurov, and likely others.