Safe Haskell	None
Language	Haskell2010

SuperRecord.Variant

Synopsis

data Variant (opts :: [*])
type family VariantMember a opts where ...
type VariantPos a opts = VariantPosHelper 1 a opts
emptyVariant :: Variant '[]
toVariant :: forall opts a pos. (KnownNat pos, VariantPos a opts ~ pos, VariantMember a opts) => a -> Variant opts
fromVariant :: forall opts a pos. (KnownNat pos, VariantPos a opts ~ pos, VariantMember a opts) => Variant opts -> Maybe a
data VariantMatch r ts where
- VariantCase :: (t -> r) -> VariantMatch r ts -> VariantMatch r (t ': ts)
- VariantEnd :: VariantMatch r '[]
- VariantWildCard :: r -> VariantMatch r ts
class VariantMatcher r opts where
- variantMatch :: Variant opts -> VariantMatch r opts -> r
shrinkVariant :: Variant (t ': ts) -> Variant ts
extendVariant :: Variant ts -> Variant (t ': ts)

Documentation

data Variant (opts :: [*]) Source #

A variant is used to express that a values type is of any of the types tracked in the type level list.

Instances

(Eq t, Eq (Variant ts)) => Eq (Variant (t ': ts)) Source #
Instance details Defined in SuperRecord.Variant Methods (==) :: Variant (t ': ts) -> Variant (t ': ts) -> Bool # (/=) :: Variant (t ': ts) -> Variant (t ': ts) -> Bool #
Eq (Variant ([] :: [Type])) Source #
Instance details Defined in SuperRecord.Variant Methods (==) :: Variant [] -> Variant [] -> Bool # (/=) :: Variant [] -> Variant [] -> Bool #
(Ord t, Ord (Variant ts)) => Ord (Variant (t ': ts)) Source #
Instance details Defined in SuperRecord.Variant Methods compare :: Variant (t ': ts) -> Variant (t ': ts) -> Ordering # (<) :: Variant (t ': ts) -> Variant (t ': ts) -> Bool # (<=) :: Variant (t ': ts) -> Variant (t ': ts) -> Bool # (>) :: Variant (t ': ts) -> Variant (t ': ts) -> Bool # (>=) :: Variant (t ': ts) -> Variant (t ': ts) -> Bool # max :: Variant (t ': ts) -> Variant (t ': ts) -> Variant (t ': ts) # min :: Variant (t ': ts) -> Variant (t ': ts) -> Variant (t ': ts) #
Ord (Variant ([] :: [Type])) Source #
Instance details Defined in SuperRecord.Variant Methods compare :: Variant [] -> Variant [] -> Ordering # (<) :: Variant [] -> Variant [] -> Bool # (<=) :: Variant [] -> Variant [] -> Bool # (>) :: Variant [] -> Variant [] -> Bool # (>=) :: Variant [] -> Variant [] -> Bool # max :: Variant [] -> Variant [] -> Variant [] # min :: Variant [] -> Variant [] -> Variant [] #
(Show t, Show (Variant ts)) => Show (Variant (t ': ts)) Source #
Instance details Defined in SuperRecord.Variant Methods showsPrec :: Int -> Variant (t ': ts) -> ShowS # show :: Variant (t ': ts) -> String # showList :: [Variant (t ': ts)] -> ShowS #
Show (Variant ([] :: [Type])) Source #
Instance details Defined in SuperRecord.Variant Methods showsPrec :: Int -> Variant [] -> ShowS # show :: Variant [] -> String # showList :: [Variant []] -> ShowS #
(ToJSON t, ToJSON (Variant ts)) => ToJSON (Variant (t ': ts)) Source #
Instance details Defined in SuperRecord.Variant Methods toJSON :: Variant (t ': ts) -> Value # toEncoding :: Variant (t ': ts) -> Encoding # toJSONList :: [Variant (t ': ts)] -> Value # toEncodingList :: [Variant (t ': ts)] -> Encoding #
ToJSON (Variant ([] :: [Type])) Source #
Instance details Defined in SuperRecord.Variant Methods toJSON :: Variant [] -> Value # toEncoding :: Variant [] -> Encoding # toJSONList :: [Variant []] -> Value # toEncodingList :: [Variant []] -> Encoding #
(FromJSON t, FromJSON (Variant ts)) => FromJSON (Variant (t ': ts)) Source #
Instance details Defined in SuperRecord.Variant Methods parseJSON :: Value -> Parser (Variant (t ': ts)) # parseJSONList :: Value -> Parser [Variant (t ': ts)] #
FromJSON (Variant ([] :: [Type])) Source #
Instance details Defined in SuperRecord.Variant Methods parseJSON :: Value -> Parser (Variant []) # parseJSONList :: Value -> Parser [Variant []] #
(NFData t, NFData (Variant ts)) => NFData (Variant (t ': ts)) Source #
Instance details Defined in SuperRecord.Variant Methods rnf :: Variant (t ': ts) -> () #
NFData (Variant ([] :: [Type])) Source #
Instance details Defined in SuperRecord.Variant Methods rnf :: Variant [] -> () #

type family VariantMember a opts where ... Source #

Equations

VariantMember x (x ': xs) = True ~ True
VariantMember x (y ': ys) = VariantMember x ys

type VariantPos a opts = VariantPosHelper 1 a opts Source #

emptyVariant :: Variant '[] Source #

An empty Variant, equivalent to `()`

toVariant :: forall opts a pos. (KnownNat pos, VariantPos a opts ~ pos, VariantMember a opts) => a -> Variant opts Source #

Convert a usual Haskell type into a Variant. It's very useful to provide type signatures for the Variants.

fromVariant :: forall opts a pos. (KnownNat pos, VariantPos a opts ~ pos, VariantMember a opts) => Variant opts -> Maybe a Source #

Convert a Variant back to a usual Haskell type, returning Nothing if the variant is not of the desired type.

data VariantMatch r ts where Source #

Constructors

VariantCase :: (t -> r) -> VariantMatch r ts -> VariantMatch r (t ': ts)
VariantEnd :: VariantMatch r '[]
VariantWildCard :: r -> VariantMatch r ts

class VariantMatcher r opts where Source #

Pattern matching helper with totality check. Note that the performance of this pattern match is roughly like a normal pattern match. (See benchmarks)

Methods

variantMatch :: Variant opts -> VariantMatch r opts -> r Source #

Instances

VariantMatcher r ([] :: [Type]) Source #
Instance details Defined in SuperRecord.Variant Methods variantMatch :: Variant [] -> VariantMatch r [] -> r Source #
VariantMatcher r ts => VariantMatcher r (t ': ts) Source #
Instance details Defined in SuperRecord.Variant Methods variantMatch :: Variant (t ': ts) -> VariantMatch r (t ': ts) -> r Source #

shrinkVariant :: Variant (t ': ts) -> Variant ts Source #

Remove an option from a Variant

extendVariant :: Variant ts -> Variant (t ': ts) Source #

Add an option to a Variant