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

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

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

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

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

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

True if the first type constructor is a newtype.

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

Generic representations that contain datatype metadata.

Name of the first constructor in a value.

>>> gconName (Just 0)
"Just"

The fixity of the first constructor.

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

True if the constructor is a record.

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

Number of constructors.

>>> gconNum @(Maybe Int)
2

Index of a constructor.

>>> gconIndex Nothing
0
>>> gconIndex (Just "test")
1

An opaque identifier for a constructor.

Identifier of a constructor.

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

Name of a constructor. See also gconName.

All constructor identifiers.

gconNum @a = length (conIdEnum @a)

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

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

Get a ConId by name.

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

Constraint synonym for Generic and GConstructors.

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

Generic representations that contain constructor metadata.

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

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

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

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

True if the generic type a is empty.

Internal definition of IsEmptyType.

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

Meta field of the M1 type constructor.

Name of the data type (MetaData).

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

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

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

Name of the constructor (MetaCons).

Fixity of the constructor (MetaCons).

True for a record constructor (MetaCons).

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

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

Unpackedness annotation of a field (MetaSel).

Strictness annotation of a field (MetaSel).

Inferred strictness of a field (MetaSel).

A placeholder for Meta values.

Remove an M1 type constructor.