Copyright	2011-2013 Edward Kmett
License	BSD3
Maintainer	Edward Kmett <ekmett@gmail.com>
Stability	experimental
Portability	portable
Safe Haskell	Safe
Language	Haskell98

Data.Functor.Trans.Tagged

Contents

Tagged values

Description

Synopsis

Tagged values

newtype TaggedT s m b Source #

A Tagged monad parameterized by:

s - the phantom type
m - the inner monad
b - the tagged value

| A TaggedT s m b value is a monadic value m 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 -> m b), a TaggedT s m 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

TagT
Fields untagT :: m b

Instances

MonadWriter w m => MonadWriter w (TaggedT k * s m) Source #
Methods writer :: (a, w) -> TaggedT k * s m a # tell :: w -> TaggedT k * s m () # listen :: TaggedT k * s m a -> TaggedT k * s m (a, w) # pass :: TaggedT k * s m (a, w -> w) -> TaggedT k * s m a #
MonadState t m => MonadState t (TaggedT k * s m) Source #
Methods get :: TaggedT k * s m t # put :: t -> TaggedT k * s m () # state :: (t -> (a, t)) -> TaggedT k * s m a #
MonadReader r m => MonadReader r (TaggedT k * s m) Source #
Methods ask :: TaggedT k * s m r # local :: (r -> r) -> TaggedT k * s m a -> TaggedT k * s m a # reader :: (r -> a) -> TaggedT k * s m a #
ComonadTrans (TaggedT k * s) Source #
Methods lower :: Comonad w => TaggedT k * s w a -> w a #
ComonadHoist (TaggedT k * s) Source #
Methods cohoist :: (Comonad w, Comonad v) => (forall x. w x -> v x) -> TaggedT k * s w a -> TaggedT k * s v a #
MonadTrans (TaggedT k * s) Source #
Methods lift :: Monad m => m a -> TaggedT k * s m a #
Monad m => Monad (TaggedT k * s m) Source #
Methods (>>=) :: TaggedT k * s m a -> (a -> TaggedT k * s m b) -> TaggedT k * s m b # (>>) :: TaggedT k * s m a -> TaggedT k * s m b -> TaggedT k * s m b # return :: a -> TaggedT k * s m a # fail :: String -> TaggedT k * s m a #
Functor m => Functor (TaggedT k * s m) Source #
Methods fmap :: (a -> b) -> TaggedT k * s m a -> TaggedT k * s m b # (<$) :: a -> TaggedT k * s m b -> TaggedT k * s m a #
MonadFix m => MonadFix (TaggedT k * s m) Source #
Methods mfix :: (a -> TaggedT k * s m a) -> TaggedT k * s m a #
Applicative m => Applicative (TaggedT k * s m) Source #
Methods pure :: a -> TaggedT k * s m a # (<>) :: TaggedT k s m (a -> b) -> TaggedT k * s m a -> TaggedT k * s m b # liftA2 :: (a -> b -> c) -> TaggedT k * s m a -> TaggedT k * s m b -> TaggedT k * s m c # (>) :: TaggedT k s m a -> TaggedT k * s m b -> TaggedT k * s m b # (<) :: TaggedT k s m a -> TaggedT k * s m b -> TaggedT k * s m a #
Foldable f => Foldable (TaggedT k * s f) Source #
Methods fold :: Monoid m => TaggedT k * s f m -> m # foldMap :: Monoid m => (a -> m) -> TaggedT k * s f a -> m # foldr :: (a -> b -> b) -> b -> TaggedT k * s f a -> b # foldr' :: (a -> b -> b) -> b -> TaggedT k * s f a -> b # foldl :: (b -> a -> b) -> b -> TaggedT k * s f a -> b # foldl' :: (b -> a -> b) -> b -> TaggedT k * s f a -> b # foldr1 :: (a -> a -> a) -> TaggedT k * s f a -> a # foldl1 :: (a -> a -> a) -> TaggedT k * s f a -> a # toList :: TaggedT k * s f a -> [a] # null :: TaggedT k * s f a -> Bool # length :: TaggedT k * s f a -> Int # elem :: Eq a => a -> TaggedT k * s f a -> Bool # maximum :: Ord a => TaggedT k * s f a -> a # minimum :: Ord a => TaggedT k * s f a -> a # sum :: Num a => TaggedT k * s f a -> a # product :: Num a => TaggedT k * s f a -> a #
Traversable f => Traversable (TaggedT k * s f) Source #
Methods traverse :: Applicative f => (a -> f b) -> TaggedT k * s f a -> f (TaggedT k * s f b) # sequenceA :: Applicative f => TaggedT k * s f (f a) -> f (TaggedT k * s f a) # mapM :: Monad m => (a -> m b) -> TaggedT k * s f a -> m (TaggedT k * s f b) # sequence :: Monad m => TaggedT k * s f (m a) -> m (TaggedT k * s f a) #
MonadIO m => MonadIO (TaggedT k * s m) Source #
Methods liftIO :: IO a -> TaggedT k * s m a #
Alternative m => Alternative (TaggedT k * s m) Source #
Methods empty :: TaggedT k * s m a # (<\|>) :: TaggedT k * s m a -> TaggedT k * s m a -> TaggedT k * s m a # some :: TaggedT k * s m a -> TaggedT k * s m [a] # many :: TaggedT k * s m a -> TaggedT k * s m [a] #
MonadPlus m => MonadPlus (TaggedT k * s m) Source #
Methods mzero :: TaggedT k * s m a # mplus :: TaggedT k * s m a -> TaggedT k * s m a -> TaggedT k * s m a #
Comonad w => Comonad (TaggedT k * s w) Source #
Methods extract :: TaggedT k * s w a -> a # duplicate :: TaggedT k * s w a -> TaggedT k * s w (TaggedT k * s w a) # extend :: (TaggedT k * s w a -> b) -> TaggedT k * s w a -> TaggedT k * s w b #
Contravariant m => Contravariant (TaggedT k * s m) Source #
Methods contramap :: (a -> b) -> TaggedT k * s m b -> TaggedT k * s m a # (>$) :: b -> TaggedT k * s m b -> TaggedT k * s m a #
Distributive f => Distributive (TaggedT k * s f) Source #
Methods distribute :: Functor f => f (TaggedT k * s f a) -> TaggedT k * s f (f a) # collect :: Functor f => (a -> TaggedT k * s f b) -> f a -> TaggedT k * s f (f b) # distributeM :: Monad m => m (TaggedT k * s f a) -> TaggedT k * s f (m a) # collectM :: Monad m => (a -> TaggedT k * s f b) -> m a -> TaggedT k * s f (m b) #
MonadThrow m => MonadThrow (TaggedT k * s m) Source #
Methods throwM :: Exception e => e -> TaggedT k * s m a #
MonadCatch m => MonadCatch (TaggedT k * s m) Source #
Methods catch :: Exception e => TaggedT k * s m a -> (e -> TaggedT k * s m a) -> TaggedT k * s m a #
MonadMask m => MonadMask (TaggedT k * s m) Source #
Methods mask :: ((forall a. TaggedT k * s m a -> TaggedT k * s m a) -> TaggedT k * s m b) -> TaggedT k * s m b # uninterruptibleMask :: ((forall a. TaggedT k * s m a -> TaggedT k * s m a) -> TaggedT k * s m b) -> TaggedT k * s m b # generalBracket :: TaggedT k * s m a -> (a -> ExitCase b -> TaggedT k * s m c) -> (a -> TaggedT k * s m b) -> TaggedT k * s m (b, c) #
MonadCont m => MonadCont (TaggedT k * s m) Source #
Methods callCC :: ((a -> TaggedT k * s m b) -> TaggedT k * s m a) -> TaggedT k * s m a #
Plus m => Plus (TaggedT k * s m) Source #
Methods zero :: TaggedT k * s m a #
Alt m => Alt (TaggedT k * s m) Source #
Methods (<!>) :: TaggedT k * s m a -> TaggedT k * s m a -> TaggedT k * s m a # some :: Applicative (TaggedT k * s m) => TaggedT k * s m a -> TaggedT k * s m [a] # many :: Applicative (TaggedT k * s m) => TaggedT k * s m a -> TaggedT k * s m [a] #
Apply m => Apply (TaggedT k * s m) Source #
Methods (<.>) :: TaggedT k * s m (a -> b) -> TaggedT k * s m a -> TaggedT k * s m b # (.>) :: TaggedT k * s m a -> TaggedT k * s m b -> TaggedT k * s m b # (<.) :: TaggedT k * s m a -> TaggedT k * s m b -> TaggedT k * s m a # liftF2 :: (a -> b -> c) -> TaggedT k * s m a -> TaggedT k * s m b -> TaggedT k * s m c #
Bind m => Bind (TaggedT k * s m) Source #
Methods (>>-) :: TaggedT k * s m a -> (a -> TaggedT k * s m b) -> TaggedT k * s m b # join :: TaggedT k * s m (TaggedT k * s m a) -> TaggedT k * s m a #
Extend f => Extend (TaggedT k * s f) Source #
Methods duplicated :: TaggedT k * s f a -> TaggedT k * s f (TaggedT k * s f a) # extended :: (TaggedT k * s f a -> b) -> TaggedT k * s f a -> TaggedT k * s f b #
Eq (m b) => Eq (TaggedT k1 k2 s m b) Source #
Methods (==) :: TaggedT k1 k2 s m b -> TaggedT k1 k2 s m b -> Bool # (/=) :: TaggedT k1 k2 s m b -> TaggedT k1 k2 s m b -> Bool #
Ord (m b) => Ord (TaggedT k1 k2 s m b) Source #
Methods compare :: TaggedT k1 k2 s m b -> TaggedT k1 k2 s m b -> Ordering # (<) :: TaggedT k1 k2 s m b -> TaggedT k1 k2 s m b -> Bool # (<=) :: TaggedT k1 k2 s m b -> TaggedT k1 k2 s m b -> Bool # (>) :: TaggedT k1 k2 s m b -> TaggedT k1 k2 s m b -> Bool # (>=) :: TaggedT k1 k2 s m b -> TaggedT k1 k2 s m b -> Bool # max :: TaggedT k1 k2 s m b -> TaggedT k1 k2 s m b -> TaggedT k1 k2 s m b # min :: TaggedT k1 k2 s m b -> TaggedT k1 k2 s m b -> TaggedT k1 k2 s m b #
Read (m b) => Read (TaggedT k1 k2 s m b) Source #
Methods readsPrec :: Int -> ReadS (TaggedT k1 k2 s m b) # readList :: ReadS [TaggedT k1 k2 s m b] # readPrec :: ReadPrec (TaggedT k1 k2 s m b) # readListPrec :: ReadPrec [TaggedT k1 k2 s m b] #
Show (m b) => Show (TaggedT k1 k2 s m b) Source #
Methods showsPrec :: Int -> TaggedT k1 k2 s m b -> ShowS # show :: TaggedT k1 k2 s m b -> String # showList :: [TaggedT k1 k2 s m b] -> ShowS #

type Tagged s b = TaggedT s Identity b Source #

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"

tag :: b -> Tagged s b Source #

Tag a value in Identity monad

tagT :: m b -> TaggedT s m b Source #

Easier to type alias for TagT

untag :: Tagged s b -> b Source #

Untag a value in Identity monad

retag :: TaggedT s m b -> TaggedT t m b Source #

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

mapTaggedT :: (m a -> n b) -> TaggedT s m a -> TaggedT s n b Source #

Lift an operation on underlying monad

reflected :: forall s m a. (Applicative m, Reifies s a) => TaggedT s m a Source #

Reflect reified value back in Applicative context

reflectedM :: forall s m a. (Monad m, Reifies s a) => TaggedT s m a Source #

Reflect reified value back in Monad context

asTaggedTypeOf :: s -> TaggedT s m b -> s Source #

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.

proxy :: Tagged s b -> Proxy s -> b Source #

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

proxyT :: TaggedT s m b -> Proxy s -> m b Source #

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

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

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

unproxyT :: (Proxy s -> m a) -> TaggedT s m a Source #

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

tagSelf :: a -> Tagged a a Source #

Tag a value with its own type.

tagTSelf :: m a -> TaggedT a m a Source #

Tag a value with its own type.