All notable changes to this project will be documented in this file.

The format is based on Keep a Changelog.

• Loosening visibility on Traversables methods to public

• Either#invert is pulled up into CoProduct2 and additionally specialized for Choice2
• CoProductN#embed
• not, used for negating predicate functions
• empty, used to test if an Iterable is empty
• groupBy, for folding an Iterable into a Map given a key function
• Applicative arrives; all functors gain applicative properties
• Traversable arrives; SingletonHList, Tuple*, Choice*, Either, Identity, and Const gain traversable properties
• TraversableOptional and TraversableIterable for adapting Optional and Iterable, respectively, to Traversable
• sequence for wrapping a traversable in an applicative during traversal
• Compose, an applicative functor that represents type-level functor composition

• Functor, Bifunctor, and Profunctor (as well as all instances) get a unification parameter
• Identity supports value equality
• Const supports value equality
• partition now only requires iterables of CoProudct2
• CoProductNs receive a unification parameter, which trickles down to Either and Choices
• Concat now represents a monoid for Iterable; previous Concat semigroup and monoid renamed to more appropriate AddAll
• Lens is now an instance of Profunctor

• ChoiceN types, representing concrete coproduct implementations that are also Functor and BiFunctor
• toMap, last, cons, prependAll, intersperse
• Tuple2/3/4#into, for applying the values in a tuple as positional arguments to a function.
• First and Last monoids over Optional
• And and Or monoids over Boolean

• CoProductN.[a-e]() static factory methods moved to equivalent ChoiceN class. Coproduct interfaces now solely represent methods, no longer have anonymous implementations, and no longer require a Functor constraint

• CoProductN#project, to project disjoint union types into tuples of Optional values
• CoProductN#converge, to drop the magnitude of a coproduct down by one type
• toCollection and size

• semigroups and monoids moved under fn2 package

• Fn1/2#adapt to switch between lambda and java.util.function types more easily
• eq, head, find, and tail
• BiPredicate
• Monoid#foldMap
• HMap#toMap to go from a heterogeneous map to a java.util.Map

• Semigroup and Monoid
• Either#invert
• partition
• Generalized coproducts implemented as CoProduct2 through CoProduct5
• Either is now a CoProduct2

• Heterogeneous list indexes arrive via Index

• Lens static factory method renaming

• Independent Lens parameter mapping via mapS, mapT, mapA, and mapB

• Initial lens support with Lens and SimpleLens types and view, set, and over functions
• Const and Identity functors
• Either#toOptional
• HMap#remove and HMap#removeAll

• All function input values become java.util.function types, and all function output values remain lambda types, for better compatibility

• HList specializations support random access lookup

• Profunctor inheritance hierarchy
• Renaming Identity to Id
• Monadic/Dyadic/TriadicFunction is now Fn1/2/3

• Either#peek
• HMap, heterogeneous maps
• Tuple2 is now also a Map.Entry

• Tuples moved under HList as specialized subtypes

• scanLeft
• HList, heterogenous lists
• Added up to Tuple5
• Either, specialized coproduct with success/failure semantics

• Better interoperability between lambda and java.util.function types

• Initial implementation of first-class curried functions
• all, any, cartesianProduct, cycle, drop, dropWhile, filter, foldLeft, foldRight, inGroupsOf, map, partial2, partial3, reduceLeft, reduceRight, repeat, take, takeWhile, unfoldr
• Monadic/Dyadic/TriadicFunction, Predicate, Tuple2, Tuple3
• Functor, BiFunctor, ProFunctor