Data.KVList

This library provide a brief implementation for extensible records. It is sensitive to the ordering of key-value items, but has simple type constraints and provides short compile time.

Constructors

We can create type level KV list as follows.

>>> :set -XOverloadedLabels -XTypeOperators
>>> import Prelude
>>> import Data.KVList (empty, KVList, (:=)((:=)), (&.), (&=))
>>> let sampleList = empty &= #foo := "str" &= #bar := 34
>>> type SampleList = KVList '[ "foo" := String, "bar" := Int ]

data KVList (kvs :: [Type])

A value with type level key.

Instances

ShowFields (KVList kvs) => Show (KVList kvs)

Defined in Data.KVList

Methods

showsPrec :: Int -> KVList kvs -> ShowS

show :: KVList kvs -> String

showList :: [KVList kvs] -> ShowS

(Eq v, Eq (KVList kvs)) => Eq (KVList ((k := v) ': kvs))

Defined in Data.KVList

Methods

(==) :: KVList ((k := v) ': kvs) -> KVList ((k := v) ': kvs) -> Bool

(/=) :: KVList ((k := v) ': kvs) -> KVList ((k := v) ': kvs) -> Bool

Eq (KVList ('[] :: [Type]))

Defined in Data.KVList

Methods

(==) :: KVList '[] -> KVList '[] -> Bool

(/=) :: KVList '[] -> KVList '[] -> Bool

data (key :: Symbol) := (value :: Type) where infix 2

Constructors

(:=) :: ListKey a -> b -> a := b infix 2

Instances

(Eq v, Eq (KVList kvs)) => Eq (KVList ((k := v) ': kvs))

Defined in Data.KVList

Methods

(==) :: KVList ((k := v) ': kvs) -> KVList ((k := v) ': kvs) -> Bool

(/=) :: KVList ((k := v) ': kvs) -> KVList ((k := v) ': kvs) -> Bool

Show value => Show (key := value)

Defined in Data.KVList

Methods

showsPrec :: Int -> (key := value) -> ShowS

show :: (key := value) -> String

showList :: [key := value] -> ShowS

(&=) :: (KnownSymbol k, Appended kvs '[k := v] ~ appended) => KVList kvs -> (k := v) -> KVList appended infixl 1

(&=>) :: (Applicative f, KnownSymbol k, Appended kvs '[k := v] ~ appended) => f (KVList kvs) -> (k := f v) -> f (KVList appended) infixl 1

Applicative version of (&=). - - >>> pure KVList.empty - >>> &=> #foo := (Just 3) - >>> &=> #bar := (Just "bar") - Just $ KVList.empty &= #foo := 3 &= #bar := "bar" - - >>> pure KVList.empty - >>> &=> #foo := (Just 3) - >>> &=> #bar := Nothing - Nothing

kvcons :: KnownSymbol k => (k := v) -> KVList kvs -> KVList ((k := v) ': kvs)

empty :: KVList '[]

singleton :: KnownSymbol k => (k := v) -> KVList '[k := v]

data ListKey (t :: Symbol)

ListKey is just a proxy, but needed to implement a non-orphan IsLabel instance. In most cases, you only need to create a ListKey instance with OverloadedLabels, such as `#foo`.

Constructors

ListKey

Instances

l ~ l' => IsLabel l (ListKey l')

Defined in Data.KVList

Methods

fromLabel :: ListKey l'

Show (ListKey t)

Defined in Data.KVList

Methods

showsPrec :: Int -> ListKey t -> ShowS

show :: ListKey t -> String

showList :: [ListKey t] -> ShowS

Eq (ListKey t)

Defined in Data.KVList

Methods

(==) :: ListKey t -> ListKey t -> Bool

(/=) :: ListKey t -> ListKey t -> Bool

Operators

get :: (KnownSymbol key, HasKey key kvs v) => ListKey key -> KVList kvs -> v

type HasKey (key :: Symbol) (kvs :: [Type]) (v :: Type) = HasKey_ key kvs kvs v

(&.) :: (KnownSymbol key, HasKey key kvs v) => KVList kvs -> ListKey key -> v infixl 9