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.

8 types
5 classes
23 values

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

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

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

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

Example1 expression

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

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

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

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

Name of the first constructor in a value.

Example1 expression

>>> gconName (Just 0)"Just"

valuegconFixity :: Constructors a => a -> Fixity

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

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

Number of constructors.

Example1 expression

>>> gconNum @(Maybe Int)2

valuegconIndex :: Constructors a => a -> Int

Index of a constructor.

Example2 expressions

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

newtypenewtype ConId (a :: k)

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

Identifier of a constructor.

valueconIdToInt :: ConId a -> Int

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

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

Name of a constructor. See also gconName.

valueconIdEnum :: Constructors a => [ConId a]

All constructor identifiers.

gconNum @a = length (conIdEnum @a)

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

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

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

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

valueconIdNamed :: ConIdNamed s a => ConId a

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

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

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

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

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) ~ '()

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

True if the generic type a is empty.

typetype IsEmptyType_ a = GIsEmptyType (Rep a)

Internal definition of IsEmptyType.

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

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 = '()

Type families

15 declarations

familytype family MetaOf (f :: Type -> Type) :: Meta where

Meta field of the M1 type constructor.

Equations

MetaOf (M1 i d f) = d

familytype family MetaDataName (m :: Meta) :: Symbol where

Name of the data type (MetaData).

Equations

MetaDataName ('MetaData n _m _p _nt) = n

familytype family MetaDataModule (m :: Meta) :: Symbol where

Name of the module where the data type is defined (MetaData)

Equations

MetaDataModule ('MetaData _n m _p _nt) = m

familytype family MetaDataPackage (m :: Meta) :: Symbol where

Name of the package where the data type is defined (MetaData)

Equations

MetaDataPackage ('MetaData _n _m p _nt) = p

familytype family MetaDataNewtype (m :: Meta) :: Bool where

True if the data type is a newtype (MetaData).

Equations

MetaDataNewtype ('MetaData _n _m _p nt) = nt

familytype family MetaConsName (m :: Meta) :: Symbol where

Name of the constructor (MetaCons).

Equations

MetaConsName ('MetaCons n _f _s) = n

familytype family MetaConsFixity (m :: Meta) :: FixityI where

Fixity of the constructor (MetaCons).

Equations

MetaConsFixity ('MetaCons _n f s) = f

familytype family MetaConsRecord (m :: Meta) :: Bool where

True for a record constructor (MetaCons).

Equations

MetaConsRecord ('MetaCons _n _f s) = s

familytype family MetaSelNameM (m :: Meta) :: Maybe Symbol where

Just the name of the record field, if it is one (MetaSel).

Equations

MetaSelNameM ('MetaSel mn _su _ss _ds) = mn

familytype family MetaSelName (m :: Meta) :: Symbol where

Name of the record field; undefined for non-record fields (MetaSel).

Equations

MetaSelName ('MetaSel ('Just n) _su _ss _ds) = n

familytype family MetaSelUnpack (m :: Meta) :: SourceUnpackedness where

Unpackedness annotation of a field (MetaSel).

Equations

MetaSelUnpack ('MetaSel _mn su _ss _ds) = su

familytype family MetaSelSourceStrictness (m :: Meta) :: SourceStrictness where

Strictness annotation of a field (MetaSel).

Equations

MetaSelSourceStrictness ('MetaSel _mn _su ss _ds) = ss

familytype family MetaSelStrictness (m :: Meta) :: DecidedStrictness where

Inferred strictness of a field (MetaSel).

Equations

MetaSelStrictness ('MetaSel _mn _su _ss ds) = ds

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

A placeholder for Meta values.

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

Remove an M1 type constructor.

Instances1UnM1

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