| Safe Haskell | None |
|---|---|
| Language | Haskell2010 |
Control.Effect.Lens
Description
Provides combinators for the lens-based manipulation of state and context types provided by the fused-effects library, similar to those provided for mtl-based monad transformers.
Synopsis
- view :: forall r a sig m. Has (Reader r) sig m => Getting a r a -> m a
- views :: forall s a b sig m. Has (Reader s) sig m => Getting a s a -> (a -> b) -> m b
- use :: forall s a sig m. Has (State s) sig m => Getting a s a -> m a
- uses :: forall s a b f sig. Has (State s) sig f => Getting a s a -> (a -> b) -> f b
- assign :: forall s a b sig m. Has (State s) sig m => ASetter s s a b -> b -> m ()
- modifying :: forall s a b sig m. Has (State s) sig m => ASetter s s a b -> (a -> b) -> m ()
- (.=) :: forall s a b sig m. Has (State s) sig m => ASetter s s a b -> b -> m ()
- (?=) :: forall s a b sig m. Has (State s) sig m => ASetter s s a (Maybe b) -> b -> m ()
- (%=) :: forall s a b sig m. Has (State s) sig m => ASetter s s a b -> (a -> b) -> m ()
- (<~) :: forall s a b sig m. Has (State s) sig m => ASetter s s a b -> m b -> m ()
- (+=) :: forall s a sig m. (Has (State s) sig m, Num a) => ASetter' s a -> a -> m ()
- (-=) :: forall s a sig m. (Has (State s) sig m, Num a) => ASetter' s a -> a -> m ()
- (*=) :: forall s a sig m. (Has (State s) sig m, Num a) => ASetter' s a -> a -> m ()
- (//=) :: forall s a sig m. (Has (State s) sig m, Fractional a) => ASetter' s a -> a -> m ()
Reader accessors
view :: forall r a sig m. Has (Reader r) sig m => Getting a r a -> m a Source #
View the value pointed to by a Getter, Lens, Traversal, or
Fold corresponding to the Reader context of the given monadic
carrier.
views :: forall s a b sig m. Has (Reader s) sig m => Getting a s a -> (a -> b) -> m b Source #
View a function of the value pointed to by a Getter or Lens,
or the result of folding over all the results of a Fold or
Traversal, when applied to the Reader context of the given
monadic carrier.
This is slightly more general in lens itself, but should suffice for our purposes.
State getters/setters
use :: forall s a sig m. Has (State s) sig m => Getting a s a -> m a Source #
Extract the target of a Lens or Getter, or use a summary of a
Fold or Traversal that points to a monoidal value.
uses :: forall s a b f sig. Has (State s) sig f => Getting a s a -> (a -> b) -> f b Source #
Use a function of the target of a Lens or Getter in the
current state, or use a summary of a Fold or Traversal that
points to a monoidal value.
assign :: forall s a b sig m. Has (State s) sig m => ASetter s s a b -> b -> m () Source #
Replace the target of a Lens (or all the targets of a Setter
or Traversal) within the current monadic state, irrespective of
the old value.
This is a prefix version of .=.
modifying :: forall s a b sig m. Has (State s) sig m => ASetter s s a b -> (a -> b) -> m () Source #
Map over the target of a Lens, or all of the targets of a Setter
or Traversal, in the current monadic state.
This is a prefix version of %=.
Infix operators
(.=) :: forall s a b sig m. Has (State s) sig m => ASetter s s a b -> b -> m () infix 4 Source #
Replace the target of a Lens (or all the targets of a Setter
or Traversal) within the current monadic state, irrespective of
the old value.
This is an infix version of assign.
(?=) :: forall s a b sig m. Has (State s) sig m => ASetter s s a (Maybe b) -> b -> m () infix 4 Source #
Replace the target of a Lens or all of the targets of a Setter or
Traversal in our monadic state with Just a new value, irrespective
of the old.
(%=) :: forall s a b sig m. Has (State s) sig m => ASetter s s a b -> (a -> b) -> m () infix 4 Source #
Map over the target of a Lens, or all of the targets of a Setter
or Traversal, in the current monadic state.
This is an infix version of modifying.
(<~) :: forall s a b sig m. Has (State s) sig m => ASetter s s a b -> m b -> m () infixr 2 Source #
Run a monadic action, and set all of the targets of a Lens, Setter
or Traversal to its result.
Mathematical operators
(+=) :: forall s a sig m. (Has (State s) sig m, Num a) => ASetter' s a -> a -> m () infix 4 Source #
Modify the target(s) of a Lens, Iso, Setter or Traversal by adding a value.
(-=) :: forall s a sig m. (Has (State s) sig m, Num a) => ASetter' s a -> a -> m () infix 4 Source #
Modify the target(s) of a Lens, Iso, Setter or Traversal by subtracting a value.
(*=) :: forall s a sig m. (Has (State s) sig m, Num a) => ASetter' s a -> a -> m () infix 4 Source #
Modify the target(s) of a Lens, Iso, Setter or Traversal by subtracting a value.
(//=) :: forall s a sig m. (Has (State s) sig m, Fractional a) => ASetter' s a -> a -> m () infix 4 Source #
Modify the target(s) of a Lens, Iso, Setter or Traversal by dividing a value.