these

An either-or-both data type.

Version on this page:	1.0.1@rev:1
LTS Haskell 20.23:	1.1.1.1@rev:6
Stackage Nightly 2023-06-04:	1.2
Latest on Hackage:	1.2

See all snapshots these appears in

BSD-3-Clause licensed by C. McCann, Oleg Grenrus

Maintained by Oleg Grenrus

This version can be pinned in stack with:these-1.0.1@sha256:7ff0f309978604015d978fb155ac4dc10a98e3d70a99aa2be8f755eb0cca4324,3191

Module documentation for 1.0.1

Data
- Data.Functor
  - Data.Functor.These
- Data.These
  - Data.These.Combinators

Depends on 10 packages(full list with versions):

aeson, assoc, base, base-compat, binary, deepseq, hashable, QuickCheck, semigroupoids, unordered-containers

Used by 5 packages in lts-14.27(full list with versions):

aeson-extra, functor-combinators, nonempty-containers, pipes-fluid, semialign

This package provides a data type These a b which can hold a value of either type or values of each type. This is usually thought of as an "inclusive or" type (contrasting Either a b as "exclusive or") or as an "outer join" type (contrasting (a, b) as "inner join").

data These a b = This a | That b | These a b

Since version 1, this package was split into parts:

semialign For Align and Zip type-classes.
semialign-indexed For SemialignWithIndex class, providing ialignWith and izipWith.
these-lens For lens combinators.
monad-chronicle For transformers variant of These.

Changes

1.0.1

add partitionEithersNE :: NonEmpty (Either a b) -> These (NonEmpty a) (NonEmpty b)

1

This is major package reogranisation. Old these were split into

these providing only These type and some combinators
these-lens providing lens combinators
semialign providing Semialign, Align, Zip, Unalign and Unzip classes
semialign-indexed providing SemialignWithIndex (izipWith and ialignWith members).
monad-chronicle providing ChronicleT and MonadChronicle

Also noticeable change is unalign :: f (These a b) -> (f a, f b). For the old f (These a b) -> (f (Maybe a), f (Maybe b)) use unzipWith (unalign . Just).

Many instances are added.
Since annotations are removed for all but these package.

0.8.1

Add Semialign Tree, Tagged, (->) e; Align Compose and Proxy instances
Allow semigroups-0.19 and hashable-1.3

0.8.0

Split align and alignWith into own class: Semialign.
ialign has default implementation
Add Semialign NonEmpty and Identity instances
Add Swap and Assoc instances (type classes from assoc package)
Move optics into Data.These.Lens module, and and some combinators Data.These.Combinators. Also some combinators are renamed, so naming is now consistent. As the result Data.These has very minimal exports.
Change type of partitionThese (nested pairs to triple)
Add partitionHereThere :: [These a b] -> ([a],[b])

0.7.6

Tigthen lower bounds
Add dependency on lens
Add assoc, reassoc, swap and Swapped instance
Add since annotations for things added in 0.7.x
Add AlignWithKey ZipList instance
Add Data.Align.Indexed module.
Add Data.Functor.These with These1 data type.
Add associativity law
Add toList property to enforce “align”-feel.
Map and IntMap Align instances implemented using merge combinators (when available)

0.7.5

Add Compose and (,) Crosswalk instances
Add bitraverseThese
GHC-8.6 support

0.7.4

QuickCheck-2.10 support: Arbitrary1/2 instances
GHC-8.2 support

0.7.3

Add salign :: (Align f, Semigroup a) => f a -> f a -> f a

0.7.2

Support aeson-1: add FromJSON1, FromJSON2 ToJSON1, and ToJSON2 These instances.

0.7.1

Add AlignWithKey in Data.Align.Key (added dependency keys)
Add These instances for
- binary: Binary
- aeson: FromJSON, ToJSON
- QuickCheck: Arbitrary, CoArbitrary, Function
- deepseq: NFData

0.7

Breaking change: Generalized Monad, Applicative instances of These and Chronicle to require only a Semigroup constraint
More efficient Align Seq implementation
Add Crosswalk Seq and Vector instances

0.6.2.1

Support quickcheck-instances-0.3.12 (tests)

0.6.2.0

Add support to bifunctors-5.1