Modulegeneric-data-1.1.0.2Haskell2010

Generic.Data.Internal.Newtype

Pack/unpack newtypes.

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.

Synopsis

classclass (Generic a, Coercible a (Old a), Newtype' a) => Newtype a

Class of newtypes. There is an instance Newtype a if and only if a is a newtype and an instance of Generic.

Instances1Newtype

(Generic a, Coercible a (Old a), Newtype' a) => Newtype aDefined in generic-data-1.1.0.2 · Generic.Data.Internal.Newtype

typetype Old a = GOld (Rep a)

The type wrapped by a newtype.

newtype Foo = Foo { bar :: Bar } deriving Generic
-- Old Foo ~ Bar

familytype family GOld (f :: Type -> Type) where

typetype Newtype' a = NewtypeErr a (MetaDataNewtype (MetaOf (Rep a)))

Use Newtype instead.

familytype family NewtypeErr a (b :: Bool) :: Constraint where

NewtypeErr a 'True = ()
NewtypeErr a 'False = TypeError (('Text "The type " ':<>: 'ShowType a) ':<>: 'Text " is not a newtype.")

valueunpack :: Newtype a => a -> Old a

Generic newtype destructor.

valuepack :: Newtype a => Old a -> a

Generic newtype constructor.