Generic.Data.Internal.Newtype

Pack/unpack newtypes.

Documentation

class (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.

Instances

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

Defined in Generic.Data.Internal.Newtype

type Old a = GOld (Rep a)

The type wrapped by a newtype.

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

type family GOld (f :: * -> *) where ...

Equations

GOld (D1 _d (C1 _c (S1 _s (K1 _i b)))) = b

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

Use Newtype instead.

type family NewtypeErr a (b :: Bool) :: Constraint where ...

Equations

NewtypeErr a True = ()

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

unpack :: Newtype a => a -> Old a

Generic newtype destructor.

pack :: Newtype a => Old a -> a

Generic newtype constructor.