Copyright	2009-2015 Edward Kmett
License	BSD3
Maintainer	Edward Kmett <ekmett@gmail.com>
Stability	experimental
Portability	portable
Safe Haskell	Safe
Language	Haskell98

Data.Tagged

Contents

Tagged values
Conversion
Proxy methods GHC dropped

Description

Synopsis

newtype Tagged s b = Tagged {
- unTagged :: b
}
retag :: Tagged s b -> Tagged t b
untag :: Tagged s b -> b
tagSelf :: a -> Tagged a a
untagSelf :: Tagged a a -> a
asTaggedTypeOf :: s -> tagged s b -> s
witness :: Tagged a b -> a -> b
proxy :: Tagged s a -> proxy s -> a
unproxy :: (Proxy s -> a) -> Tagged s a
tagWith :: proxy s -> a -> Tagged s a
reproxy :: proxy a -> Proxy b

Tagged values

newtype Tagged s b #

A Tagged s b value is a value b with an attached phantom type s. This can be used in place of the more traditional but less safe idiom of passing in an undefined value with the type, because unlike an (s -> b), a Tagged s b can't try to use the argument s as a real value.

Moreover, you don't have to rely on the compiler to inline away the extra argument, because the newtype is "free"

Tagged has kind k -> * -> * if the compiler supports PolyKinds, therefore there is an extra k showing in the instance haddocks that may cause confusion.

Constructors

Tagged
Fields unTagged :: b

Instances

Instances details

Bitraversable (Tagged :: Type -> Type -> Type) #
Instance details Defined in Data.Tagged Methods bitraverse :: Applicative f => (a -> f c) -> (b -> f d) -> Tagged a b -> f (Tagged c d) #
Bifoldable (Tagged :: Type -> Type -> Type) #
Instance details Defined in Data.Tagged Methods bifold :: Monoid m => Tagged m m -> m # bifoldMap :: Monoid m => (a -> m) -> (b -> m) -> Tagged a b -> m # bifoldr :: (a -> c -> c) -> (b -> c -> c) -> c -> Tagged a b -> c # bifoldl :: (c -> a -> c) -> (c -> b -> c) -> c -> Tagged a b -> c #
Bifunctor (Tagged :: Type -> Type -> Type) #
Instance details Defined in Data.Tagged Methods bimap :: (a -> b) -> (c -> d) -> Tagged a c -> Tagged b d # first :: (a -> b) -> Tagged a c -> Tagged b c # second :: (b -> c) -> Tagged a b -> Tagged a c #
Eq2 (Tagged :: Type -> Type -> Type) #
Instance details Defined in Data.Tagged Methods liftEq2 :: (a -> b -> Bool) -> (c -> d -> Bool) -> Tagged a c -> Tagged b d -> Bool #
Ord2 (Tagged :: Type -> Type -> Type) #
Instance details Defined in Data.Tagged Methods liftCompare2 :: (a -> b -> Ordering) -> (c -> d -> Ordering) -> Tagged a c -> Tagged b d -> Ordering #
Read2 (Tagged :: Type -> Type -> Type) #
Instance details Defined in Data.Tagged Methods liftReadsPrec2 :: (Int -> ReadS a) -> ReadS [a] -> (Int -> ReadS b) -> ReadS [b] -> Int -> ReadS (Tagged a b) # liftReadList2 :: (Int -> ReadS a) -> ReadS [a] -> (Int -> ReadS b) -> ReadS [b] -> ReadS [Tagged a b] # liftReadPrec2 :: ReadPrec a -> ReadPrec [a] -> ReadPrec b -> ReadPrec [b] -> ReadPrec (Tagged a b) # liftReadListPrec2 :: ReadPrec a -> ReadPrec [a] -> ReadPrec b -> ReadPrec [b] -> ReadPrec [Tagged a b] #
Show2 (Tagged :: Type -> Type -> Type) #
Instance details Defined in Data.Tagged Methods liftShowsPrec2 :: (Int -> a -> ShowS) -> ([a] -> ShowS) -> (Int -> b -> ShowS) -> ([b] -> ShowS) -> Int -> Tagged a b -> ShowS # liftShowList2 :: (Int -> a -> ShowS) -> ([a] -> ShowS) -> (Int -> b -> ShowS) -> ([b] -> ShowS) -> [Tagged a b] -> ShowS #
Generic1 (Tagged s :: Type -> Type) #
Instance details Defined in Data.Tagged Associated Types type Rep1 (Tagged s) :: k -> Type # Methods from1 :: forall (a :: k). Tagged s a -> Rep1 (Tagged s) a # to1 :: forall (a :: k). Rep1 (Tagged s) a -> Tagged s a #
Monad (Tagged s) #
Instance details Defined in Data.Tagged Methods (>>=) :: Tagged s a -> (a -> Tagged s b) -> Tagged s b # (>>) :: Tagged s a -> Tagged s b -> Tagged s b # return :: a -> Tagged s a #
Functor (Tagged s) #
Instance details Defined in Data.Tagged Methods fmap :: (a -> b) -> Tagged s a -> Tagged s b # (<$) :: a -> Tagged s b -> Tagged s a #
Applicative (Tagged s) #
Instance details Defined in Data.Tagged Methods pure :: a -> Tagged s a # (<>) :: Tagged s (a -> b) -> Tagged s a -> Tagged s b # liftA2 :: (a -> b -> c) -> Tagged s a -> Tagged s b -> Tagged s c # (>) :: Tagged s a -> Tagged s b -> Tagged s b # (<*) :: Tagged s a -> Tagged s b -> Tagged s a #
Foldable (Tagged s) #
Instance details Defined in Data.Tagged Methods fold :: Monoid m => Tagged s m -> m # foldMap :: Monoid m => (a -> m) -> Tagged s a -> m # foldMap' :: Monoid m => (a -> m) -> Tagged s a -> m # foldr :: (a -> b -> b) -> b -> Tagged s a -> b # foldr' :: (a -> b -> b) -> b -> Tagged s a -> b # foldl :: (b -> a -> b) -> b -> Tagged s a -> b # foldl' :: (b -> a -> b) -> b -> Tagged s a -> b # foldr1 :: (a -> a -> a) -> Tagged s a -> a # foldl1 :: (a -> a -> a) -> Tagged s a -> a # toList :: Tagged s a -> [a] # null :: Tagged s a -> Bool # length :: Tagged s a -> Int # elem :: Eq a => a -> Tagged s a -> Bool # maximum :: Ord a => Tagged s a -> a # minimum :: Ord a => Tagged s a -> a # sum :: Num a => Tagged s a -> a # product :: Num a => Tagged s a -> a #
Traversable (Tagged s) #
Instance details Defined in Data.Tagged Methods traverse :: Applicative f => (a -> f b) -> Tagged s a -> f (Tagged s b) # sequenceA :: Applicative f => Tagged s (f a) -> f (Tagged s a) # mapM :: Monad m => (a -> m b) -> Tagged s a -> m (Tagged s b) # sequence :: Monad m => Tagged s (m a) -> m (Tagged s a) #
Eq1 (Tagged s) #
Instance details Defined in Data.Tagged Methods liftEq :: (a -> b -> Bool) -> Tagged s a -> Tagged s b -> Bool #
Ord1 (Tagged s) #
Instance details Defined in Data.Tagged Methods liftCompare :: (a -> b -> Ordering) -> Tagged s a -> Tagged s b -> Ordering #
Read1 (Tagged s) #
Instance details Defined in Data.Tagged Methods liftReadsPrec :: (Int -> ReadS a) -> ReadS [a] -> Int -> ReadS (Tagged s a) # liftReadList :: (Int -> ReadS a) -> ReadS [a] -> ReadS [Tagged s a] # liftReadPrec :: ReadPrec a -> ReadPrec [a] -> ReadPrec (Tagged s a) # liftReadListPrec :: ReadPrec a -> ReadPrec [a] -> ReadPrec [Tagged s a] #
Show1 (Tagged s) #
Instance details Defined in Data.Tagged Methods liftShowsPrec :: (Int -> a -> ShowS) -> ([a] -> ShowS) -> Int -> Tagged s a -> ShowS # liftShowList :: (Int -> a -> ShowS) -> ([a] -> ShowS) -> [Tagged s a] -> ShowS #
Bounded b => Bounded (Tagged s b) #
Instance details Defined in Data.Tagged Methods minBound :: Tagged s b # maxBound :: Tagged s b #
Enum a => Enum (Tagged s a) #
Instance details Defined in Data.Tagged Methods succ :: Tagged s a -> Tagged s a # pred :: Tagged s a -> Tagged s a # toEnum :: Int -> Tagged s a # fromEnum :: Tagged s a -> Int # enumFrom :: Tagged s a -> [Tagged s a] # enumFromThen :: Tagged s a -> Tagged s a -> [Tagged s a] # enumFromTo :: Tagged s a -> Tagged s a -> [Tagged s a] # enumFromThenTo :: Tagged s a -> Tagged s a -> Tagged s a -> [Tagged s a] #
Eq b => Eq (Tagged s b) #
Instance details Defined in Data.Tagged Methods (==) :: Tagged s b -> Tagged s b -> Bool # (/=) :: Tagged s b -> Tagged s b -> Bool #
Floating a => Floating (Tagged s a) #
Instance details Defined in Data.Tagged Methods pi :: Tagged s a # exp :: Tagged s a -> Tagged s a # log :: Tagged s a -> Tagged s a # sqrt :: Tagged s a -> Tagged s a # (**) :: Tagged s a -> Tagged s a -> Tagged s a # logBase :: Tagged s a -> Tagged s a -> Tagged s a # sin :: Tagged s a -> Tagged s a # cos :: Tagged s a -> Tagged s a # tan :: Tagged s a -> Tagged s a # asin :: Tagged s a -> Tagged s a # acos :: Tagged s a -> Tagged s a # atan :: Tagged s a -> Tagged s a # sinh :: Tagged s a -> Tagged s a # cosh :: Tagged s a -> Tagged s a # tanh :: Tagged s a -> Tagged s a # asinh :: Tagged s a -> Tagged s a # acosh :: Tagged s a -> Tagged s a # atanh :: Tagged s a -> Tagged s a # log1p :: Tagged s a -> Tagged s a # expm1 :: Tagged s a -> Tagged s a # log1pexp :: Tagged s a -> Tagged s a # log1mexp :: Tagged s a -> Tagged s a #
Fractional a => Fractional (Tagged s a) #
Instance details Defined in Data.Tagged Methods (/) :: Tagged s a -> Tagged s a -> Tagged s a # recip :: Tagged s a -> Tagged s a # fromRational :: Rational -> Tagged s a #
Integral a => Integral (Tagged s a) #
Instance details Defined in Data.Tagged Methods quot :: Tagged s a -> Tagged s a -> Tagged s a # rem :: Tagged s a -> Tagged s a -> Tagged s a # div :: Tagged s a -> Tagged s a -> Tagged s a # mod :: Tagged s a -> Tagged s a -> Tagged s a # quotRem :: Tagged s a -> Tagged s a -> (Tagged s a, Tagged s a) # divMod :: Tagged s a -> Tagged s a -> (Tagged s a, Tagged s a) # toInteger :: Tagged s a -> Integer #
(Data s, Data b) => Data (Tagged s b) #
Instance details Defined in Data.Tagged Methods gfoldl :: (forall d b0. Data d => c (d -> b0) -> d -> c b0) -> (forall g. g -> c g) -> Tagged s b -> c (Tagged s b) # gunfold :: (forall b0 r. Data b0 => c (b0 -> r) -> c r) -> (forall r. r -> c r) -> Constr -> c (Tagged s b) # toConstr :: Tagged s b -> Constr # dataTypeOf :: Tagged s b -> DataType # dataCast1 :: Typeable t => (forall d. Data d => c (t d)) -> Maybe (c (Tagged s b)) # dataCast2 :: Typeable t => (forall d e. (Data d, Data e) => c (t d e)) -> Maybe (c (Tagged s b)) # gmapT :: (forall b0. Data b0 => b0 -> b0) -> Tagged s b -> Tagged s b # gmapQl :: (r -> r' -> r) -> r -> (forall d. Data d => d -> r') -> Tagged s b -> r # gmapQr :: forall r r'. (r' -> r -> r) -> r -> (forall d. Data d => d -> r') -> Tagged s b -> r # gmapQ :: (forall d. Data d => d -> u) -> Tagged s b -> [u] # gmapQi :: Int -> (forall d. Data d => d -> u) -> Tagged s b -> u # gmapM :: Monad m => (forall d. Data d => d -> m d) -> Tagged s b -> m (Tagged s b) # gmapMp :: MonadPlus m => (forall d. Data d => d -> m d) -> Tagged s b -> m (Tagged s b) # gmapMo :: MonadPlus m => (forall d. Data d => d -> m d) -> Tagged s b -> m (Tagged s b) #
Num a => Num (Tagged s a) #
Instance details Defined in Data.Tagged Methods (+) :: Tagged s a -> Tagged s a -> Tagged s a # (-) :: Tagged s a -> Tagged s a -> Tagged s a # (*) :: Tagged s a -> Tagged s a -> Tagged s a # negate :: Tagged s a -> Tagged s a # abs :: Tagged s a -> Tagged s a # signum :: Tagged s a -> Tagged s a # fromInteger :: Integer -> Tagged s a #
Ord b => Ord (Tagged s b) #
Instance details Defined in Data.Tagged Methods compare :: Tagged s b -> Tagged s b -> Ordering # (<) :: Tagged s b -> Tagged s b -> Bool # (<=) :: Tagged s b -> Tagged s b -> Bool # (>) :: Tagged s b -> Tagged s b -> Bool # (>=) :: Tagged s b -> Tagged s b -> Bool # max :: Tagged s b -> Tagged s b -> Tagged s b # min :: Tagged s b -> Tagged s b -> Tagged s b #
Read b => Read (Tagged s b) #
Instance details Defined in Data.Tagged Methods readsPrec :: Int -> ReadS (Tagged s b) # readList :: ReadS [Tagged s b] # readPrec :: ReadPrec (Tagged s b) # readListPrec :: ReadPrec [Tagged s b] #
Real a => Real (Tagged s a) #
Instance details Defined in Data.Tagged Methods toRational :: Tagged s a -> Rational #
RealFloat a => RealFloat (Tagged s a) #
Instance details Defined in Data.Tagged Methods floatRadix :: Tagged s a -> Integer # floatDigits :: Tagged s a -> Int # floatRange :: Tagged s a -> (Int, Int) # decodeFloat :: Tagged s a -> (Integer, Int) # encodeFloat :: Integer -> Int -> Tagged s a # exponent :: Tagged s a -> Int # significand :: Tagged s a -> Tagged s a # scaleFloat :: Int -> Tagged s a -> Tagged s a # isNaN :: Tagged s a -> Bool # isInfinite :: Tagged s a -> Bool # isDenormalized :: Tagged s a -> Bool # isNegativeZero :: Tagged s a -> Bool # isIEEE :: Tagged s a -> Bool # atan2 :: Tagged s a -> Tagged s a -> Tagged s a #
RealFrac a => RealFrac (Tagged s a) #
Instance details Defined in Data.Tagged Methods properFraction :: Integral b => Tagged s a -> (b, Tagged s a) # truncate :: Integral b => Tagged s a -> b # round :: Integral b => Tagged s a -> b # ceiling :: Integral b => Tagged s a -> b # floor :: Integral b => Tagged s a -> b #
Show b => Show (Tagged s b) #
Instance details Defined in Data.Tagged Methods showsPrec :: Int -> Tagged s b -> ShowS # show :: Tagged s b -> String # showList :: [Tagged s b] -> ShowS #
Ix b => Ix (Tagged s b) #
Instance details Defined in Data.Tagged Methods range :: (Tagged s b, Tagged s b) -> [Tagged s b] # index :: (Tagged s b, Tagged s b) -> Tagged s b -> Int # unsafeIndex :: (Tagged s b, Tagged s b) -> Tagged s b -> Int # inRange :: (Tagged s b, Tagged s b) -> Tagged s b -> Bool # rangeSize :: (Tagged s b, Tagged s b) -> Int # unsafeRangeSize :: (Tagged s b, Tagged s b) -> Int #
IsString a => IsString (Tagged s a) #
Instance details Defined in Data.Tagged Methods fromString :: String -> Tagged s a #
Generic (Tagged s b) #
Instance details Defined in Data.Tagged Associated Types type Rep (Tagged s b) :: Type -> Type # Methods from :: Tagged s b -> Rep (Tagged s b) x # to :: Rep (Tagged s b) x -> Tagged s b #
Semigroup a => Semigroup (Tagged s a) #
Instance details Defined in Data.Tagged Methods (<>) :: Tagged s a -> Tagged s a -> Tagged s a # sconcat :: NonEmpty (Tagged s a) -> Tagged s a # stimes :: Integral b => b -> Tagged s a -> Tagged s a #
(Semigroup a, Monoid a) => Monoid (Tagged s a) #
Instance details Defined in Data.Tagged Methods mempty :: Tagged s a # mappend :: Tagged s a -> Tagged s a -> Tagged s a # mconcat :: [Tagged s a] -> Tagged s a #
Storable a => Storable (Tagged s a) #
Instance details Defined in Data.Tagged Methods sizeOf :: Tagged s a -> Int # alignment :: Tagged s a -> Int # peekElemOff :: Ptr (Tagged s a) -> Int -> IO (Tagged s a) # pokeElemOff :: Ptr (Tagged s a) -> Int -> Tagged s a -> IO () # peekByteOff :: Ptr b -> Int -> IO (Tagged s a) # pokeByteOff :: Ptr b -> Int -> Tagged s a -> IO () # peek :: Ptr (Tagged s a) -> IO (Tagged s a) # poke :: Ptr (Tagged s a) -> Tagged s a -> IO () #
Bits a => Bits (Tagged s a) #
Instance details Defined in Data.Tagged Methods (.&.) :: Tagged s a -> Tagged s a -> Tagged s a # (.\|.) :: Tagged s a -> Tagged s a -> Tagged s a # xor :: Tagged s a -> Tagged s a -> Tagged s a # complement :: Tagged s a -> Tagged s a # shift :: Tagged s a -> Int -> Tagged s a # rotate :: Tagged s a -> Int -> Tagged s a # zeroBits :: Tagged s a # bit :: Int -> Tagged s a # setBit :: Tagged s a -> Int -> Tagged s a # clearBit :: Tagged s a -> Int -> Tagged s a # complementBit :: Tagged s a -> Int -> Tagged s a # testBit :: Tagged s a -> Int -> Bool # bitSizeMaybe :: Tagged s a -> Maybe Int # bitSize :: Tagged s a -> Int # isSigned :: Tagged s a -> Bool # shiftL :: Tagged s a -> Int -> Tagged s a # unsafeShiftL :: Tagged s a -> Int -> Tagged s a # shiftR :: Tagged s a -> Int -> Tagged s a # unsafeShiftR :: Tagged s a -> Int -> Tagged s a # rotateL :: Tagged s a -> Int -> Tagged s a # rotateR :: Tagged s a -> Int -> Tagged s a # popCount :: Tagged s a -> Int #
FiniteBits a => FiniteBits (Tagged s a) #
Instance details Defined in Data.Tagged Methods finiteBitSize :: Tagged s a -> Int # countLeadingZeros :: Tagged s a -> Int # countTrailingZeros :: Tagged s a -> Int #
NFData b => NFData (Tagged s b) #
Instance details Defined in Data.Tagged Methods rnf :: Tagged s b -> () #
type Rep1 (Tagged s :: Type -> Type) #
Instance details Defined in Data.Tagged type Rep1 (Tagged s :: Type -> Type) = D1 ('MetaData "Tagged" "Data.Tagged" "tagged-0.8.6.1" 'True) (C1 ('MetaCons "Tagged" 'PrefixI 'True) (S1 ('MetaSel ('Just "unTagged") 'NoSourceUnpackedness 'NoSourceStrictness 'DecidedLazy) Par1))
type Rep (Tagged s b) #
Instance details Defined in Data.Tagged type Rep (Tagged s b) = D1 ('MetaData "Tagged" "Data.Tagged" "tagged-0.8.6.1" 'True) (C1 ('MetaCons "Tagged" 'PrefixI 'True) (S1 ('MetaSel ('Just "unTagged") 'NoSourceUnpackedness 'NoSourceStrictness 'DecidedLazy) (Rec0 b)))

retag :: Tagged s b -> Tagged t b #

Some times you need to change the tag you have lying around. Idiomatic usage is to make a new combinator for the relationship between the tags that you want to enforce, and define that combinator using retag.

data Succ n
retagSucc :: Tagged n a -> Tagged (Succ n) a
retagSucc = retag

untag :: Tagged s b -> b #

Alias for unTagged

tagSelf :: a -> Tagged a a #

Tag a value with its own type.

untagSelf :: Tagged a a -> a #

untagSelf is a type-restricted version of untag.

asTaggedTypeOf :: s -> tagged s b -> s #

asTaggedTypeOf is a type-restricted version of const. It is usually used as an infix operator, and its typing forces its first argument (which is usually overloaded) to have the same type as the tag of the second.

witness :: Tagged a b -> a -> b #

Conversion

proxy :: Tagged s a -> proxy s -> a #

Convert from a Tagged representation to a representation based on a Proxy.

unproxy :: (Proxy s -> a) -> Tagged s a #

Convert from a representation based on a Proxy to a Tagged representation.

tagWith :: proxy s -> a -> Tagged s a #

Another way to convert a proxy to a tag.

Proxy methods GHC dropped

reproxy :: proxy a -> Proxy b #

Some times you need to change the proxy you have lying around. Idiomatic usage is to make a new combinator for the relationship between the proxies that you want to enforce, and define that combinator using reproxy.

data Succ n
reproxySucc :: proxy n -> Proxy (Succ n)
reproxySucc = reproxy