Safe Haskell | Safe-Inferred |
---|---|
Language | Haskell2010 |
- view :: MonadReader s m => Getting a s a -> m a
- use :: MonadState s m => Getting a s a -> m a
- (.=) :: MonadState s m => ASetter s s a b -> b -> m ()
- (%=) :: MonadState s m => ASetter s s a b -> (a -> b) -> m ()
- (+=) :: (MonadState s m, Num a) => ASetter s s a a -> a -> m ()
- (-=) :: (MonadState s m, Num a) => ASetter s s a a -> a -> m ()
- (*=) :: (MonadState s m, Num a) => ASetter s s a a -> a -> m ()
- (//=) :: (MonadState s m, Fractional a) => ASetter s s a a -> a -> m ()
Documentation
view :: MonadReader s m => Getting a s a -> m a Source
view
is a synonym for (^.
), generalised for MonadReader
(since
functions are instances of the MonadReader
class).
>>>
view _1 (1, 2)
1
It's often used when dealing with environment, for instance:
doSomething :: (MonadReader
Config m) => m Int doSomething = do thingy <-view
setting1 -- same as “asks
(^. setting1)” anotherThingy <-view
setting2 ...
use :: MonadState s m => Getting a s a -> m a Source
(.=) :: MonadState s m => ASetter s s a b -> b -> m () infix 4 Source
(%=) :: MonadState s m => ASetter s s a b -> (a -> b) -> m () infix 4 Source
(+=) :: (MonadState s m, Num a) => ASetter s s a a -> a -> m () infix 4 Source
(-=) :: (MonadState s m, Num a) => ASetter s s a a -> a -> m () infix 4 Source
(*=) :: (MonadState s m, Num a) => ASetter s s a a -> a -> m () infix 4 Source
(//=) :: (MonadState s m, Fractional a) => ASetter s s a a -> a -> m () infix 4 Source
Divide the target by a number.
l /= x = l %= (x)