Distribution.Compat.Newtype

Per Conor McBride, the Newtype typeclass represents the packing and unpacking of a newtype, and allows you to operatate under that newtype with functions such as ala.

Documentation

class Newtype n o | n -> o where

The FunctionalDependencies version of Newtype type-class.

Note: for actual newtypes the implementation can be pack = coerce; unpack = coerce. We don't have default implementation, because Cabal have to support older than base >= 4.7 compilers. Also, Newtype could witness a non-structural isomorphism.

Minimal complete definition

pack, unpack

Methods

pack :: o -> n

unpack :: n -> o

Instances

Newtype FilePathNT String

Defined in Distribution.Parsec.Newtypes

Methods

pack :: String -> FilePathNT

unpack :: FilePathNT -> String

Newtype FreeText String

Defined in Distribution.Parsec.Newtypes

Methods

pack :: String -> FreeText

unpack :: FreeText -> String

Newtype Token' String

Defined in Distribution.Parsec.Newtypes

Methods

pack :: String -> Token'

unpack :: Token' -> String

Newtype Token String

Defined in Distribution.Parsec.Newtypes

Methods

pack :: String -> Token

unpack :: Token -> String

Newtype TestedWith (CompilerFlavor, VersionRange)

Defined in Distribution.Parsec.Newtypes

Methods

pack :: (CompilerFlavor, VersionRange) -> TestedWith

unpack :: TestedWith -> (CompilerFlavor, VersionRange)

Newtype SpecLicense (Either License License)

Defined in Distribution.Parsec.Newtypes

Methods

pack :: Either License0 License -> SpecLicense

unpack :: SpecLicense -> Either License0 License

Newtype SpecVersion (Either Version VersionRange)

Defined in Distribution.Parsec.Newtypes

Methods

pack :: Either Version VersionRange -> SpecVersion

unpack :: SpecVersion -> Either Version VersionRange

Newtype (Identity a) a

Defined in Distribution.Compat.Newtype

Methods

pack :: a -> Identity a

unpack :: Identity a -> a

Newtype (Sum a) a

Defined in Distribution.Compat.Newtype

Methods

pack :: a -> Sum a

unpack :: Sum a -> a

Newtype (Product a) a

Defined in Distribution.Compat.Newtype

Methods

pack :: a -> Product a

unpack :: Product a -> a

Newtype (MQuoted a) a

Defined in Distribution.Parsec.Newtypes

Methods

pack :: a -> MQuoted a

unpack :: MQuoted a -> a

Newtype (Endo a) (a -> a)

Defined in Distribution.Compat.Newtype

Methods

pack :: (a -> a) -> Endo a

unpack :: Endo a -> a -> a

Newtype (List sep wrapper a) [a]

Defined in Distribution.Parsec.Newtypes

Methods

pack :: [a] -> List sep wrapper a

unpack :: List sep wrapper a -> [a]

ala :: (Newtype n o, Newtype n' o') => (o -> n) -> ((o -> n) -> b -> n') -> b -> o'

>>> ala Sum foldMap [1, 2, 3, 4 :: Int]
10

Note: the user supplied function for the newtype is ignored.

>>> ala (Sum . (+1)) foldMap [1, 2, 3, 4 :: Int]
10

alaf :: (Newtype n o, Newtype n' o') => (o -> n) -> ((a -> n) -> b -> n') -> (a -> o) -> b -> o'

>>> alaf Sum foldMap length ["cabal", "install"]
12

Note: as with ala, the user supplied function for the newtype is ignored.

pack' :: Newtype n o => (o -> n) -> o -> n

Variant of pack, which takes a phantom type.

unpack' :: Newtype n o => (o -> n) -> n -> o

Variant of pack, which takes a phantom type.