Copyright	(c) 2011-2015 diagrams-core team (see LICENSE)
License	BSD-style (see LICENSE)
Maintainer	diagrams-discuss@googlegroups.com
Safe Haskell	Safe-Inferred
Language	Haskell2010

Data.Monoid.Split

Description

Sometimes we want to accumulate values from some monoid, but have the ability to introduce a "split" which separates values on either side. Only the rightmost split is kept. For example,

a b c | d e | f g h == a b c d e | f g h

In the diagrams graphics framework this is used when accumulating transformations to be applied to primitive diagrams: the freeze operation introduces a split, since only transformations occurring outside the freeze should be applied to attributes.

Synopsis

data Split m
- = M m
- | m :| m
split :: Monoid m => Split m
unsplit :: Semigroup m => Split m -> m

Documentation

data Split m Source #

A value of type Split m is either a single m, or a pair of m's separated by a divider. Single m's combine as usual; single m's combine with split values by combining with the value on the appropriate side; when two split values meet only the rightmost split is kept, with both the values from the left split combining with the left-hand value of the right split.

Data.Monoid.Cut is similar, but uses a different scheme for composition. Split uses the asymmetric constructor :|, and Cut the symmetric constructor :||:, to emphasize the inherent asymmetry of Split and symmetry of Cut. Split keeps only the rightmost split and combines everything on the left; Cut keeps the outermost splits and throws away everything in between.

Constructors

M m
m :\| m infix 5

Instances

Instances details

Functor Split Source #
Instance details Defined in Data.Monoid.Split Methods fmap :: (a -> b) -> Split a -> Split b # (<$) :: a -> Split b -> Split a #
Foldable Split Source #
Instance details Defined in Data.Monoid.Split Methods fold :: Monoid m => Split m -> m # foldMap :: Monoid m => (a -> m) -> Split a -> m # foldMap' :: Monoid m => (a -> m) -> Split a -> m # foldr :: (a -> b -> b) -> b -> Split a -> b # foldr' :: (a -> b -> b) -> b -> Split a -> b # foldl :: (b -> a -> b) -> b -> Split a -> b # foldl' :: (b -> a -> b) -> b -> Split a -> b # foldr1 :: (a -> a -> a) -> Split a -> a # foldl1 :: (a -> a -> a) -> Split a -> a # toList :: Split a -> [a] # null :: Split a -> Bool # length :: Split a -> Int # elem :: Eq a => a -> Split a -> Bool # maximum :: Ord a => Split a -> a # minimum :: Ord a => Split a -> a # sum :: Num a => Split a -> a # product :: Num a => Split a -> a #
Traversable Split Source #
Instance details Defined in Data.Monoid.Split Methods traverse :: Applicative f => (a -> f b) -> Split a -> f (Split b) # sequenceA :: Applicative f => Split (f a) -> f (Split a) # mapM :: Monad m => (a -> m b) -> Split a -> m (Split b) # sequence :: Monad m => Split (m a) -> m (Split a) #
Eq m => Eq (Split m) Source #
Instance details Defined in Data.Monoid.Split Methods (==) :: Split m -> Split m -> Bool # (/=) :: Split m -> Split m -> Bool #
Data m => Data (Split m) Source #
Instance details Defined in Data.Monoid.Split Methods gfoldl :: (forall d b. Data d => c (d -> b) -> d -> c b) -> (forall g. g -> c g) -> Split m -> c (Split m) # gunfold :: (forall b r. Data b => c (b -> r) -> c r) -> (forall r. r -> c r) -> Constr -> c (Split m) # toConstr :: Split m -> Constr # dataTypeOf :: Split m -> DataType # dataCast1 :: Typeable t => (forall d. Data d => c (t d)) -> Maybe (c (Split m)) # dataCast2 :: Typeable t => (forall d e. (Data d, Data e) => c (t d e)) -> Maybe (c (Split m)) # gmapT :: (forall b. Data b => b -> b) -> Split m -> Split m # gmapQl :: (r -> r' -> r) -> r -> (forall d. Data d => d -> r') -> Split m -> r # gmapQr :: forall r r'. (r' -> r -> r) -> r -> (forall d. Data d => d -> r') -> Split m -> r # gmapQ :: (forall d. Data d => d -> u) -> Split m -> [u] # gmapQi :: Int -> (forall d. Data d => d -> u) -> Split m -> u # gmapM :: Monad m0 => (forall d. Data d => d -> m0 d) -> Split m -> m0 (Split m) # gmapMp :: MonadPlus m0 => (forall d. Data d => d -> m0 d) -> Split m -> m0 (Split m) # gmapMo :: MonadPlus m0 => (forall d. Data d => d -> m0 d) -> Split m -> m0 (Split m) #
Read m => Read (Split m) Source #
Instance details Defined in Data.Monoid.Split Methods readsPrec :: Int -> ReadS (Split m) # readList :: ReadS [Split m] # readPrec :: ReadPrec (Split m) # readListPrec :: ReadPrec [Split m] #
Show m => Show (Split m) Source #
Instance details Defined in Data.Monoid.Split Methods showsPrec :: Int -> Split m -> ShowS # show :: Split m -> String # showList :: [Split m] -> ShowS #
Semigroup m => Semigroup (Split m) Source #	If `m` is a `Semigroup`, then `Split m` is a semigroup which combines values on either side of a split, keeping only the rightmost split.
Instance details Defined in Data.Monoid.Split Methods (<>) :: Split m -> Split m -> Split m # sconcat :: NonEmpty (Split m) -> Split m # stimes :: Integral b => b -> Split m -> Split m #
(Semigroup m, Monoid m) => Monoid (Split m) Source #
Instance details Defined in Data.Monoid.Split Methods mempty :: Split m # mappend :: Split m -> Split m -> Split m # mconcat :: [Split m] -> Split m #
Action m n => Action (Split m) n Source #	By default, the action of a split monoid is the same as for the underlying monoid, as if the split were removed.
Instance details Defined in Data.Monoid.Split Methods act :: Split m -> n -> n Source #

split :: Monoid m => Split m Source #

A convenient name for mempty :| mempty, so M a <> split <> M b == a :| b.

unsplit :: Semigroup m => Split m -> m Source #

"Unsplit" a split monoid value, combining the two values into one (or returning the single value if there is no split).