Data.Generic.HKD.Types

Documentation

newtype HKD (structure :: Type) (f :: Type -> Type)

Higher-kinded data (HKD) is the design pattern in which every field in our type is wrapped in some functor f:

  data User f
   = User
       { name :: f String
       , age  :: f Int
       }

Depending on the functor, we can get different behaviours: with Maybe, we get a partial structure; with Validation, we get a piecemeal validator; and so on. The HKD newtype allows us to lift any type into an HKD-style API via its generic representation.

>>> :set -XDeriveGeneric -XTypeApplications
>>> :{
data User
  = User { name :: String, age :: Int }
  deriving Generic
:}

The HKD type is indexed by our choice of functor and the structure we're lifting. In other words, we can define a synonym for our behaviour:

>>> import Data.Monoid (Last (..))
>>> type Partial a = HKD a Last

... and then we're ready to go!

>>> mempty @(Partial User)
User {name = Last {getLast = Nothing}, age = Last {getLast = Nothing}}

>>> mempty @(HKD (Int, Bool) [])
(,) [] []

Constructors

HKD

Fields

• runHKD :: HKD_ f structure Void

Instances

(ProductB (HKD structure), ConstraintsB (HKD structure), GProductBC (Rep structure)) => ProductBC (HKD structure :: (Type -> Type) -> Type)

Defined in Data.Generic.HKD.Types

Methods

bdicts :: AllB c (HKD structure) => HKD structure (Dict c)

(FunctorB (HKD structure), GConstraintsB (Rep structure)) => ConstraintsB (HKD structure :: (Type -> Type) -> Type)

Defined in Data.Generic.HKD.Types

Associated Types

type AllB c (HKD structure) :: Constraint

Methods

baddDicts :: AllB c (HKD structure) => HKD structure f -> HKD structure (Product (Dict c) f)

(FunctorB (HKD structure), GProductB (Rep structure)) => ProductB (HKD structure :: (Type -> Type) -> Type)

Defined in Data.Generic.HKD.Types

Methods

bprod :: HKD structure f -> HKD structure g -> HKD structure (Product f g)

buniq :: (forall (a :: k). f a) -> HKD structure f

(FunctorB (HKD structure), GTraversableB (Rep structure)) => TraversableB (HKD structure :: (Type -> Type) -> Type)

Defined in Data.Generic.HKD.Types

Methods

btraverse :: Applicative t => (forall (a :: k). f a -> t (g a)) -> HKD structure f -> t (HKD structure g)

GFunctorB (Rep structure) => FunctorB (HKD structure :: (Type -> Type) -> Type)

Defined in Data.Generic.HKD.Types

Methods

bmap :: (forall (a :: k). f a -> g a) -> HKD structure f -> HKD structure g

(Eq tuple, Generic xs, Tuple f xs tuple) => Eq (HKD xs f)

Defined in Data.Generic.HKD.Types

Methods

(==) :: HKD xs f -> HKD xs f -> Bool

(/=) :: HKD xs f -> HKD xs f -> Bool

(Ord tuple, Generic xs, Tuple f xs tuple) => Ord (HKD xs f)

Defined in Data.Generic.HKD.Types

Methods

compare :: HKD xs f -> HKD xs f -> Ordering

(<) :: HKD xs f -> HKD xs f -> Bool

(<=) :: HKD xs f -> HKD xs f -> Bool

(>) :: HKD xs f -> HKD xs f -> Bool

(>=) :: HKD xs f -> HKD xs f -> Bool

max :: HKD xs f -> HKD xs f -> HKD xs f

min :: HKD xs f -> HKD xs f -> HKD xs f

(Generic structure, GShow True (HKD_ f structure)) => Show (HKD structure f)

Defined in Data.Generic.HKD.Types

Methods

showsPrec :: Int -> HKD structure f -> ShowS

show :: HKD structure f -> String

showList :: [HKD structure f] -> ShowS

(Semigroup tuple, Generic xs, Tuple f xs tuple) => Semigroup (HKD xs f)

Defined in Data.Generic.HKD.Types

Methods

(<>) :: HKD xs f -> HKD xs f -> HKD xs f

sconcat :: NonEmpty (HKD xs f) -> HKD xs f

stimes :: Integral b => b -> HKD xs f -> HKD xs f

(Monoid tuple, Generic xs, Tuple f xs tuple) => Monoid (HKD xs f)

Defined in Data.Generic.HKD.Types

Methods

mempty :: HKD xs f

mappend :: HKD xs f -> HKD xs f -> HKD xs f

mconcat :: [HKD xs f] -> HKD xs f

(Generic structure, Function tuple, Tuple f structure tuple) => Function (HKD structure f)

Defined in Data.Generic.HKD.Types

Methods

function :: (HKD structure f -> b) -> HKD structure f :-> b

(Arbitrary tuple, GToTuple (HKD_ f structure) tuple) => Arbitrary (HKD structure f)

Defined in Data.Generic.HKD.Types

Methods

arbitrary :: Gen (HKD structure f)

shrink :: HKD structure f -> [HKD structure f]

(CoArbitrary tuple, GToTuple (HKD_ f structure) tuple) => CoArbitrary (HKD structure f)

Defined in Data.Generic.HKD.Types

Methods

coarbitrary :: HKD structure f -> Gen b -> Gen b

type AllB (c :: Type -> Constraint) (HKD structure :: (Type -> Type) -> Type)

Defined in Data.Generic.HKD.Types

type AllB (c :: Type -> Constraint) (HKD structure :: (Type -> Type) -> Type)

type HKD_ (f :: Type -> Type) (structure :: Type) = GHKD_ f (Rep structure)

Calculate the "partial representation" of a type.

type family GHKD_ (f :: Type -> Type) (rep :: Type -> Type) = (output :: Type -> Type) | output -> f rep where ...

Calculate the "partial representation" of a generic rep.

Equations

GHKD_ f (M1 index meta inner) = M1 index meta (GHKD_ f inner)

GHKD_ f (left :*: right) = GHKD_ f left :*: GHKD_ f right

GHKD_ f (K1 index value) = K1 index (f value)

GHKD_ f (left :+: right) = GHKD_ f left :+: GHKD_ f right