Modulegeneric-data-1.1.0.2Haskell2010

Generic.Data.Internal.Meta

Type metadata accessors

Type names, constructor names...

Warning

This is an internal module: it is not subject to any versioning policy, breaking changes can happen at any time.

If something here seems useful, please report it or create a pull request to export it from an external module.

Contents

Constructor information on generic representations
Find a constructor tag by name
Check that a type is not empty
Type families

Synopsis

value gdatatypeName
value gmoduleName
value gpackageName
value gisNewtype
value fromDatatype
class GDatatype
value gconName
value gconFixity
value gconIsRecord
value gconNum
value gconIndex
newtype ConId
value conId
value conIdToInt
value conIdToString
value conIdEnum
value conIdMin
value conIdMax
value conIdNamed
class Constructors
class ConIdNamed
newtype GConId
value gConIdToInt
value toConId
value fromConId
value reGConId
value gConIdMin
value gConIdMax
class GConstructors
type ConIdNamed'
type GConIdNamed
family GConIdNamed'
family GConIdNamedIf
class NonEmptyType
type NonEmptyType_
family GIsEmptyType
type IsEmptyType
type IsEmptyType_
family ErrorIfEmpty
family MetaOf
family MetaDataName
family MetaDataModule
family MetaDataPackage
family MetaDataNewtype
family MetaConsName
family MetaConsFixity
family MetaConsRecord
family MetaSelNameM
family MetaSelName
family MetaSelUnpack
family MetaSelSourceStrictness
family MetaSelStrictness
type DummyMeta
family UnM1

Packagegeneric-data-1.1.0.2
Exports54
LanguageHaskell2010
LicenceMIT
SourceMeta.hs

Example3 expressions

>>> :set -XDataKinds -XTypeApplications>>> import Control.Applicative (ZipList)>>> import Data.Monoid (Sum(..))

valuegdatatypeName :: (Generic a, GDatatype (Rep a)) => String

Source#

Name of the first data constructor in a type as a string.

Example1 expression

>>> gdatatypeName @(Maybe Int)"Maybe"

valuegmoduleName :: (Generic a, GDatatype (Rep a)) => String

Source#

Name of the module where the first type constructor is defined.

Example1 expression

>>> gmoduleName @(ZipList Int)"Control.Applicative"

valuegpackageName :: (Generic a, GDatatype (Rep a)) => String

Source#

Name of the package where the first type constructor is defined.

Example1 expression

>>> gpackageName @(Maybe Int)"base"

valuegisNewtype :: (Generic a, GDatatype (Rep a)) => Bool

Source#

True if the first type constructor is a newtype.

Example2 expressions

>>> gisNewtype @[Int]False>>> gisNewtype @(ZipList Int)True

valuefromDatatype :: Datatype d => (M1 D d Proxy () -> r) -> r

classclass GDatatype (f :: k) where

Source#

Generic representations that contain datatype metadata.

Methods

gDatatypeName :: String
gModuleName :: String
gPackageName :: String
gIsNewtype :: Bool

Instances1GDatatype

Datatype d => GDatatype (M1 D d f)Defined in generic-data-1.1.0.2 · Generic.Data.Internal.Meta

valuegconName :: Constructors a => a -> String

Source#

Name of the first constructor in a value.

Example1 expression

>>> gconName (Just 0)"Just"

valuegconFixity :: Constructors a => a -> Fixity

Source#

The fixity of the first constructor.

Example3 expressions

>>> import GHC.Generics ((:*:)(..))>>> gconFixity (Just 0)Prefix>>> gconFixity ([] :*: id)Infix RightAssociative 6

valuegconIsRecord :: Constructors a => a -> Bool

Source#

True if the constructor is a record.

Example2 expressions

>>> gconIsRecord (Just 0)False>>> gconIsRecord (Sum 0)   -- Note:  newtype Sum a = Sum { getSum :: a }True

valuegconNum :: Constructors a => Int

Source#

Number of constructors.

Example1 expression

>>> gconNum @(Maybe Int)2

valuegconIndex :: Constructors a => a -> Int

Source#

Index of a constructor.

Example2 expressions

>>> gconIndex Nothing0>>> gconIndex (Just "test")1

newtypenewtype ConId (a :: k)

Source#

An opaque identifier for a constructor.

Constructors

ConId Int

Instances3Eq, Ord, Show

Eq (ConId a)Defined in generic-data-1.1.0.2 · Generic.Data.Internal.Meta
Ord (ConId a)Defined in generic-data-1.1.0.2 · Generic.Data.Internal.Meta
Show (ConId a)Defined in generic-data-1.1.0.2 · Generic.Data.Internal.Meta

valueconId :: Constructors a => a -> ConId a

Source#

Identifier of a constructor.

valueconIdToInt :: ConId a -> Int

Source#

Index of a constructor, given its identifier. See also gconIndex.

valueconIdToString :: Constructors a => ConId a -> String

Source#

Name of a constructor. See also gconName.

valueconIdEnum :: Constructors a => [ConId a]

Source#

All constructor identifiers.

gconNum @a = length (conIdEnum @a)

valueconIdMin :: (Constructors a, NonEmptyType "conIdMin" a) => ConId a

Source#

The first constructor. This must not be called on an empty type.

valueconIdMax :: (Constructors a, NonEmptyType "conIdMax" a) => ConId a

Source#

The last constructor. This must not be called on an empty type.

valueconIdNamed :: ConIdNamed s a => ConId a

Source#

Get a ConId by name.

Example2 expressions

>>> conIdNamed @"Nothing" :: ConId (Maybe Int)ConId 0>>> conIdNamed @"Just"    :: ConId (Maybe Int)ConId 1

classclass (Generic a, GConstructors (Rep a)) => Constructors a

Source#

Constraint synonym for Generic and GConstructors.

Instances1Constructors

(Generic a, GConstructors (Rep a)) => Constructors aDefined in generic-data-1.1.0.2 · Generic.Data.Internal.Meta

classclass (Generic a, KnownNat (ConIdNamed' n a)) => ConIdNamed (n :: Symbol) a

Source#

Constraint synonym for generic types a with a constructor named n.

Instances1ConIdNamed

(Generic a, KnownNat (ConIdNamed' n a)) => ConIdNamed n aDefined in generic-data-1.1.0.2 · Generic.Data.Internal.Meta

Constructor information on generic representations

newtypenewtype GConId (r :: k)

Constructors

GConId Int

Instances2Eq, Ord

Eq (GConId r)Defined in generic-data-1.1.0.2 · Generic.Data.Internal.Meta
Ord (GConId r)Defined in generic-data-1.1.0.2 · Generic.Data.Internal.Meta

valuegConIdToInt :: GConId r -> Int

valuetoConId :: Generic a => GConId (Rep a) -> ConId a

valuefromConId :: Generic a => ConId a -> GConId (Rep a)

valuereGConId :: GConId r -> GConId s

valuegConIdMin :: GConstructors r => GConId r

valuegConIdMax :: GConstructors r => GConId r

classclass GConstructors (r :: k -> Type) where

Source#

Generic representations that contain constructor metadata.

Methods

gConIdToString :: GConId r -> String
gConId :: r p -> GConId r
gConNum :: Int
gConFixity :: r p -> Fixity
gConIsRecord :: r p -> Bool

Instances4GConstructors

GConstructors V1Defined in generic-data-1.1.0.2 · Generic.Data.Internal.Meta
(GConstructors f, GConstructors g) => GConstructors (f :+: g)Defined in generic-data-1.1.0.2 · Generic.Data.Internal.Meta
GConstructors f => GConstructors (M1 D c f)Defined in generic-data-1.1.0.2 · Generic.Data.Internal.Meta
Constructor c => GConstructors (M1 C c f)Defined in generic-data-1.1.0.2 · Generic.Data.Internal.Meta

Find a constructor tag by name

typetype ConIdNamed' (n :: Symbol) t = GConIdNamedIf n t (GConIdNamed n (Rep t))

typetype GConIdNamed (n :: Symbol) (f :: k -> Type) = GConIdNamed' n f 0 'Nothing

familytype family GConIdNamed' (n :: Symbol) (f :: k -> Type) (i :: Nat) (o :: Maybe Nat) :: Maybe Nat where

Equations

GConIdNamed' n (M1 D _c f) i r = GConIdNamed' n f i r
GConIdNamed' n (f :+: g) i r = GConIdNamed' n f i (GConIdNamed' n g (i + NConstructors f) r)
GConIdNamed' n (M1 C ('MetaCons n _f _s) _g) i _r = 'Just i
GConIdNamed' n (M1 C ('MetaCons _n _f _s) _g) _i r = r
GConIdNamed' _n V1 _i r = r

familytype family GConIdNamedIf (n :: Symbol) t (o :: Maybe Nat) :: Nat where

Equations

GConIdNamedIf _n _t ('Just i) = i
GConIdNamedIf n t 'Nothing = TypeError ((('Text "No constructor named " ':<>: 'ShowType n) ':<>: 'Text " in generic type ") ':<>: 'ShowType t)

Check that a type is not empty

classclass NonEmptyType_ fname a => NonEmptyType (fname :: Symbol) a

Source#

Constraint that a generic type a is not empty. Producing an error message otherwise.

The Symbol parameter fname is used only for error messages.

It is implied by the simpler constraint IsEmptyType a ~ 'False

Instances1NonEmptyType

NonEmptyType_ fname a => NonEmptyType fname aDefined in generic-data-1.1.0.2 · Generic.Data.Internal.Meta

typetype NonEmptyType_ (fname :: Symbol) a = ErrorIfEmpty fname a (IsEmptyType a) ~ '()

Source#

Internal definition of NonEmptyType. It is implied by the simpler constraint IsEmptyType a ~ 'False.

Example2 expressions

>>> :set -XTypeFamilies>>> :{conIdMin' :: (Constructors a, IsEmptyType a ~ 'False) => ConId aconIdMin' = conIdMin:}

Example1 expression

>>> :{conIdMax' :: (Constructors a, IsEmptyType a ~ 'False) => ConId aconIdMax' = conIdMax:}

familytype family GIsEmptyType (r :: k -> Type) :: Bool where

Equations

GIsEmptyType (M1 D _d V1) = 'True
GIsEmptyType (M1 D _d (M1 C _c _f)) = 'False
GIsEmptyType (M1 D _d (_f :+: _g)) = 'False

typetype IsEmptyType a = IsEmptyType_ a

Source#

True if the generic type a is empty.

typetype IsEmptyType_ a = GIsEmptyType (Rep a)

Source#

Internal definition of IsEmptyType.

familytype family ErrorIfEmpty (fname :: Symbol) a (b :: Bool) :: () where

Source#

Throw an error if the boolean b is true, meaning that the type a is empty.

Example:

ghci> data E deriving Generic
ghci> conIdMin :: ConId E

Error message:

The function 'conIdMin' cannot be used with the empty type E

Equations

ErrorIfEmpty fname a 'True = TypeError ((('Text "The function '" ':<>: 'Text fname) ':<>: 'Text "' cannot be used with the empty type ") ':<>: 'ShowType a)
ErrorIfEmpty fname a 'False = '()

MetaSelStrictness ('MetaSel _mn _su _ss ds) = ds

typetype DummyMeta = 'MetaData "" "" "" 'False

Source#

A placeholder for Meta values.

familytype family UnM1 (f :: k -> Type) :: k -> Type

Source#

Remove an M1 type constructor.

Instances1UnM1

type UnM1 (M1 i c f) = fDefined in generic-data-1.1.0.2 · Generic.Data.Internal.Meta