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

Data.Monoid.Deletable

Description

A monoid transformer that allows deleting information from a concatenation of monoidal values.

Synopsis

Documentation

data Deletable m #

If m is a Monoid, then Deletable m (intuitively speaking) adds two distinguished new elements [ and ], such that an occurrence of [ "deletes" everything from it to the next ]. For example,

abc[def]gh == abcgh

This is all you really need to know to use Deletable m values; to understand the actual implementation, read on.

To properly deal with nesting and associativity we need to be able to assign meanings to things like [[, ][, and so on. (We cannot just define, say, [[ == [, since then ([[)] == [] == id but [([]) == [id == [.) Formally, elements of Deletable m are triples of the form (r, m, l) representing words ]^r m [^l. When combining two triples (r1, m1, l1) and (r2, m2, l2) there are three cases:

If l1 == r2 then the [s from the left and ]s from the right exactly cancel, and we are left with (r1, m1 <> m2, l2).
If l1 < r2 then all of the [s cancel with some of the ]s, but m1 is still inside the remaining ]s and is deleted, yielding (r1 + r2 - l1, m2, l2)
The remaining case is symmetric with the second.

Constructors

Deletable Int m Int

Instances

Functor Deletable #
Methods fmap :: (a -> b) -> Deletable a -> Deletable b # (<$) :: a -> Deletable b -> Deletable a #
Foldable Deletable #
Methods fold :: Monoid m => Deletable m -> m # foldMap :: Monoid m => (a -> m) -> Deletable a -> m # foldr :: (a -> b -> b) -> b -> Deletable a -> b # foldr' :: (a -> b -> b) -> b -> Deletable a -> b # foldl :: (b -> a -> b) -> b -> Deletable a -> b # foldl' :: (b -> a -> b) -> b -> Deletable a -> b # foldr1 :: (a -> a -> a) -> Deletable a -> a # foldl1 :: (a -> a -> a) -> Deletable a -> a # toList :: Deletable a -> [a] # null :: Deletable a -> Bool # length :: Deletable a -> Int # elem :: Eq a => a -> Deletable a -> Bool # maximum :: Ord a => Deletable a -> a # minimum :: Ord a => Deletable a -> a # sum :: Num a => Deletable a -> a # product :: Num a => Deletable a -> a #
Traversable Deletable #
Methods traverse :: Applicative f => (a -> f b) -> Deletable a -> f (Deletable b) # sequenceA :: Applicative f => Deletable (f a) -> f (Deletable a) # mapM :: Monad m => (a -> m b) -> Deletable a -> m (Deletable b) # sequence :: Monad m => Deletable (m a) -> m (Deletable a) #
Data m => Data (Deletable m) #
Methods gfoldl :: (forall d b. Data d => c (d -> b) -> d -> c b) -> (forall g. g -> c g) -> Deletable m -> c (Deletable m) # gunfold :: (forall b r. Data b => c (b -> r) -> c r) -> (forall r. r -> c r) -> Constr -> c (Deletable m) # toConstr :: Deletable m -> Constr # dataTypeOf :: Deletable m -> DataType # dataCast1 :: Typeable (* -> ) t => (forall d. Data d => c (t d)) -> Maybe (c (Deletable m)) # dataCast2 :: Typeable ( -> * -> *) t => (forall d e. (Data d, Data e) => c (t d e)) -> Maybe (c (Deletable m)) # gmapT :: (forall b. Data b => b -> b) -> Deletable m -> Deletable m # gmapQl :: (r -> r' -> r) -> r -> (forall d. Data d => d -> r') -> Deletable m -> r # gmapQr :: (r' -> r -> r) -> r -> (forall d. Data d => d -> r') -> Deletable m -> r # gmapQ :: (forall d. Data d => d -> u) -> Deletable m -> [u] # gmapQi :: Int -> (forall d. Data d => d -> u) -> Deletable m -> u # gmapM :: Monad m => (forall d. Data d => d -> m d) -> Deletable m -> m (Deletable m) # gmapMp :: MonadPlus m => (forall d. Data d => d -> m d) -> Deletable m -> m (Deletable m) # gmapMo :: MonadPlus m => (forall d. Data d => d -> m d) -> Deletable m -> m (Deletable m) #
Read m => Read (Deletable m) #
Methods readsPrec :: Int -> ReadS (Deletable m) # readList :: ReadS [Deletable m] # readPrec :: ReadPrec (Deletable m) # readListPrec :: ReadPrec [Deletable m] #
Show m => Show (Deletable m) #
Methods showsPrec :: Int -> Deletable m -> ShowS # show :: Deletable m -> String # showList :: [Deletable m] -> ShowS #
Semigroup m => Semigroup (Deletable m) #
Methods (<>) :: Deletable m -> Deletable m -> Deletable m # sconcat :: NonEmpty (Deletable m) -> Deletable m # stimes :: Integral b => b -> Deletable m -> Deletable m #
(Semigroup m, Monoid m) => Monoid (Deletable m) #
Methods mempty :: Deletable m # mappend :: Deletable m -> Deletable m -> Deletable m # mconcat :: [Deletable m] -> Deletable m #

unDelete :: Deletable m -> m #

Project the wrapped value out of a Deletable value.

toDeletable :: m -> Deletable m #

Inject a value into a Deletable wrapper. Satisfies the property

unDelete . toDeletable === id

deleteL :: Monoid m => Deletable m #

A "left bracket", which causes everything between it and the next right bracket to be deleted.

deleteR :: Monoid m => Deletable m #

A "right bracket", denoting the end of the section that should be deleted.