| Safe Haskell | Safe-Inferred |
|---|
Control.Reference.Predefined
Contents
Description
Predefined references for commonly used data structures and reference generators.
When defining lenses one should use the more general types. For instance Lens instead of the more strict Lens'. This way references with different m1 and m2 monads can be combined if there is a monad m' for MMorph m1 m' and MMorph m2 m'.
- self :: Lens a b a b
- emptyRef :: Simple RefPlus s a
- traverse :: Traversable t => Traversal (t a) (t b) a b
- iso :: (a -> b) -> (b -> a) -> Lens a a b b
- lens :: (s -> a) -> (b -> s -> t) -> Lens s t a b
- partial :: (s -> Either t (a, b -> t)) -> Partial s t a b
- simplePartial :: (s -> Maybe (a, a -> s)) -> Partial s s a a
- fromLens :: (forall f. Functor f => (a -> f b) -> s -> f t) -> Lens s t a b
- fromTraversal :: (forall f. Applicative f => (a -> f b) -> s -> f t) -> Traversal s t a b
- filtered :: (a -> Bool) -> Simple RefPlus a a
- just :: Partial (Maybe a) (Maybe b) a b
- right :: Partial (Either a b) (Either a c) b c
- left :: Partial (Either a c) (Either b c) a b
- anyway :: Lens (Either a a) (Either b b) a b
- both :: Traversal (a, a) (b, b) a b
- _head :: Simple Partial [a] a
- _tail :: Simple Partial [a] [a]
- class Association e where
- type AssocIndex e :: *
- type AssocElem e :: *
- element :: AssocIndex e -> Simple Partial e (AssocElem e)
- data Console = Console
- consoleLine :: Simple IOLens Console String
- mvar :: (Functor w, Applicative w, Monad w, MMorph IO w, MonadBaseControl IO w, Functor r, Applicative r, Monad r, MMorph IO r) => Simple (Reference w r) (MVar a) a
- chan :: Simple IOLens (Chan a) a
- ioref :: Simple IOLens (IORef a) a
- state :: forall s m a. Monad m => Simple (StateLens s m) a s
Trivial references
emptyRef :: Simple RefPlus s aSource
An empty reference that do not traverse anything
emptyRef &+& a = a &+& emptyRef = a
a & emptyRef = emptyRef & a = emptyRef
Reference generators
traverse :: Traversable t => Traversal (t a) (t b) a bSource
Generates a traversal for any Traversable Functor
simplePartial :: (s -> Maybe (a, a -> s)) -> Partial s s a aSource
Creates a simple partial lens
fromLens :: (forall f. Functor f => (a -> f b) -> s -> f t) -> Lens s t a bSource
Clones a lens from Control.Lens
fromTraversal :: (forall f. Applicative f => (a -> f b) -> s -> f t) -> Traversal s t a bSource
Clones a traversal from Control.Lens
filtered :: (a -> Bool) -> Simple RefPlus a aSource
Filters the traversed elements with a given predicate. Has specific versions for traversals and partial lenses.
References for simple data structures
right :: Partial (Either a b) (Either a c) b cSource
A partial lens to access the right option of an Either
left :: Partial (Either a c) (Either b c) a bSource
A partial lens to access the left option of an Either
anyway :: Lens (Either a a) (Either b b) a bSource
Access the value that is in the left or right state of an Either
class Association e whereSource
Lenses for given values in a data structure that is indexed by keys.
Instances
| Association [a] | |
| Ord k => Association (Map k v) |
Stateful references
A dummy object to interact with the user through the console.
Constructors
| Console |
consoleLine :: Simple IOLens Console StringSource
Interacts with a line of text on the console. Values set are printed, getting is reading from the console.
mvar :: (Functor w, Applicative w, Monad w, MMorph IO w, MonadBaseControl IO w, Functor r, Applicative r, Monad r, MMorph IO r) => Simple (Reference w r) (MVar a) aSource
Access a value inside an MVar. Setting is not atomic. If there is two supplier that may set the accessed value, one may block and can corrupt the following updates.
Reads and updates are done in sequence, always using consistent data.