Copyright	2009-2013 Edward Kmett
License	BSD3
Maintainer	Edward Kmett <ekmett@gmail.com>
Stability	experimental
Portability	portable
Safe Haskell	Trustworthy
Language	Haskell98

Data.Tagged

Contents

Tagged values
Conversion

Description

Synopsis

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"

Constructors

Tagged
Fields unTagged :: b

Instances

Bifunctor (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 #
Monad (Tagged k s) #
Methods (>>=) :: Tagged k s a -> (a -> Tagged k s b) -> Tagged k s b # (>>) :: Tagged k s a -> Tagged k s b -> Tagged k s b # return :: a -> Tagged k s a # fail :: String -> Tagged k s a #
Functor (Tagged k s) #
Methods fmap :: (a -> b) -> Tagged k s a -> Tagged k s b # (<$) :: a -> Tagged k s b -> Tagged k s a #
Applicative (Tagged k s) #
Methods pure :: a -> Tagged k s a # (<>) :: Tagged k s (a -> b) -> Tagged k s a -> Tagged k s b # liftA2 :: (a -> b -> c) -> Tagged k s a -> Tagged k s b -> Tagged k s c # (>) :: Tagged k s a -> Tagged k s b -> Tagged k s b # (<*) :: Tagged k s a -> Tagged k s b -> Tagged k s a #
Foldable (Tagged k s) #
Methods fold :: Monoid m => Tagged k s m -> m # foldMap :: Monoid m => (a -> m) -> Tagged k s a -> m # foldr :: (a -> b -> b) -> b -> Tagged k s a -> b # foldr' :: (a -> b -> b) -> b -> Tagged k s a -> b # foldl :: (b -> a -> b) -> b -> Tagged k s a -> b # foldl' :: (b -> a -> b) -> b -> Tagged k s a -> b # foldr1 :: (a -> a -> a) -> Tagged k s a -> a # foldl1 :: (a -> a -> a) -> Tagged k s a -> a # toList :: Tagged k s a -> [a] # null :: Tagged k s a -> Bool # length :: Tagged k s a -> Int # elem :: Eq a => a -> Tagged k s a -> Bool # maximum :: Ord a => Tagged k s a -> a # minimum :: Ord a => Tagged k s a -> a # sum :: Num a => Tagged k s a -> a # product :: Num a => Tagged k s a -> a #
Traversable (Tagged k s) #
Methods traverse :: Applicative f => (a -> f b) -> Tagged k s a -> f (Tagged k s b) # sequenceA :: Applicative f => Tagged k s (f a) -> f (Tagged k s a) # mapM :: Monad m => (a -> m b) -> Tagged k s a -> m (Tagged k s b) # sequence :: Monad m => Tagged k s (m a) -> m (Tagged k s a) #
Bounded b => Bounded (Tagged k s b) #
Methods minBound :: Tagged k s b # maxBound :: Tagged k s b #
Enum a => Enum (Tagged k s a) #
Methods succ :: Tagged k s a -> Tagged k s a # pred :: Tagged k s a -> Tagged k s a # toEnum :: Int -> Tagged k s a # fromEnum :: Tagged k s a -> Int # enumFrom :: Tagged k s a -> [Tagged k s a] # enumFromThen :: Tagged k s a -> Tagged k s a -> [Tagged k s a] # enumFromTo :: Tagged k s a -> Tagged k s a -> [Tagged k s a] # enumFromThenTo :: Tagged k s a -> Tagged k s a -> Tagged k s a -> [Tagged k s a] #
Eq b => Eq (Tagged k s b) #
Methods (==) :: Tagged k s b -> Tagged k s b -> Bool # (/=) :: Tagged k s b -> Tagged k s b -> Bool #
Floating a => Floating (Tagged k s a) #
Methods pi :: Tagged k s a # exp :: Tagged k s a -> Tagged k s a # log :: Tagged k s a -> Tagged k s a # sqrt :: Tagged k s a -> Tagged k s a # (**) :: Tagged k s a -> Tagged k s a -> Tagged k s a # logBase :: Tagged k s a -> Tagged k s a -> Tagged k s a # sin :: Tagged k s a -> Tagged k s a # cos :: Tagged k s a -> Tagged k s a # tan :: Tagged k s a -> Tagged k s a # asin :: Tagged k s a -> Tagged k s a # acos :: Tagged k s a -> Tagged k s a # atan :: Tagged k s a -> Tagged k s a # sinh :: Tagged k s a -> Tagged k s a # cosh :: Tagged k s a -> Tagged k s a # tanh :: Tagged k s a -> Tagged k s a # asinh :: Tagged k s a -> Tagged k s a # acosh :: Tagged k s a -> Tagged k s a # atanh :: Tagged k s a -> Tagged k s a # log1p :: Tagged k s a -> Tagged k s a # expm1 :: Tagged k s a -> Tagged k s a # log1pexp :: Tagged k s a -> Tagged k s a # log1mexp :: Tagged k s a -> Tagged k s a #
Fractional a => Fractional (Tagged k s a) #
Methods (/) :: Tagged k s a -> Tagged k s a -> Tagged k s a # recip :: Tagged k s a -> Tagged k s a # fromRational :: Rational -> Tagged k s a #
Integral a => Integral (Tagged k s a) #
Methods quot :: Tagged k s a -> Tagged k s a -> Tagged k s a # rem :: Tagged k s a -> Tagged k s a -> Tagged k s a # div :: Tagged k s a -> Tagged k s a -> Tagged k s a # mod :: Tagged k s a -> Tagged k s a -> Tagged k s a # quotRem :: Tagged k s a -> Tagged k s a -> (Tagged k s a, Tagged k s a) # divMod :: Tagged k s a -> Tagged k s a -> (Tagged k s a, Tagged k s a) # toInteger :: Tagged k s a -> Integer #
(Data s, Data b) => Data (Tagged * s b) #
Methods gfoldl :: (forall d a. Data d => c (d -> a) -> d -> c a) -> (forall g. g -> c g) -> Tagged * s b -> c (Tagged * s b) # gunfold :: (forall a r. Data a => c (a -> 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 a. Data a => a -> a) -> Tagged * s b -> Tagged * s b # gmapQl :: (r -> r' -> r) -> r -> (forall d. Data d => d -> r') -> Tagged * s b -> r # gmapQr :: (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 k s a) #
Methods (+) :: Tagged k s a -> Tagged k s a -> Tagged k s a # (-) :: Tagged k s a -> Tagged k s a -> Tagged k s a # (*) :: Tagged k s a -> Tagged k s a -> Tagged k s a # negate :: Tagged k s a -> Tagged k s a # abs :: Tagged k s a -> Tagged k s a # signum :: Tagged k s a -> Tagged k s a # fromInteger :: Integer -> Tagged k s a #
Ord b => Ord (Tagged k s b) #
Methods compare :: Tagged k s b -> Tagged k s b -> Ordering # (<) :: Tagged k s b -> Tagged k s b -> Bool # (<=) :: Tagged k s b -> Tagged k s b -> Bool # (>) :: Tagged k s b -> Tagged k s b -> Bool # (>=) :: Tagged k s b -> Tagged k s b -> Bool # max :: Tagged k s b -> Tagged k s b -> Tagged k s b # min :: Tagged k s b -> Tagged k s b -> Tagged k s b #
Read b => Read (Tagged k s b) #
Methods readsPrec :: Int -> ReadS (Tagged k s b) # readList :: ReadS [Tagged k s b] # readPrec :: ReadPrec (Tagged k s b) # readListPrec :: ReadPrec [Tagged k s b] #
Real a => Real (Tagged k s a) #
Methods toRational :: Tagged k s a -> Rational #
RealFloat a => RealFloat (Tagged k s a) #
Methods floatRadix :: Tagged k s a -> Integer # floatDigits :: Tagged k s a -> Int # floatRange :: Tagged k s a -> (Int, Int) # decodeFloat :: Tagged k s a -> (Integer, Int) # encodeFloat :: Integer -> Int -> Tagged k s a # exponent :: Tagged k s a -> Int # significand :: Tagged k s a -> Tagged k s a # scaleFloat :: Int -> Tagged k s a -> Tagged k s a # isNaN :: Tagged k s a -> Bool # isInfinite :: Tagged k s a -> Bool # isDenormalized :: Tagged k s a -> Bool # isNegativeZero :: Tagged k s a -> Bool # isIEEE :: Tagged k s a -> Bool # atan2 :: Tagged k s a -> Tagged k s a -> Tagged k s a #
RealFrac a => RealFrac (Tagged k s a) #
Methods properFraction :: Integral b => Tagged k s a -> (b, Tagged k s a) # truncate :: Integral b => Tagged k s a -> b # round :: Integral b => Tagged k s a -> b # ceiling :: Integral b => Tagged k s a -> b # floor :: Integral b => Tagged k s a -> b #
Show b => Show (Tagged k s b) #
Methods showsPrec :: Int -> Tagged k s b -> ShowS # show :: Tagged k s b -> String # showList :: [Tagged k s b] -> ShowS #
Ix b => Ix (Tagged k s b) #
Methods range :: (Tagged k s b, Tagged k s b) -> [Tagged k s b] # index :: (Tagged k s b, Tagged k s b) -> Tagged k s b -> Int # unsafeIndex :: (Tagged k s b, Tagged k s b) -> Tagged k s b -> Int inRange :: (Tagged k s b, Tagged k s b) -> Tagged k s b -> Bool # rangeSize :: (Tagged k s b, Tagged k s b) -> Int # unsafeRangeSize :: (Tagged k s b, Tagged k s b) -> Int
Monoid a => Monoid (Tagged k s a) #
Methods mempty :: Tagged k s a # mappend :: Tagged k s a -> Tagged k s a -> Tagged k s a # mconcat :: [Tagged k s a] -> Tagged k s a #

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.