Agda.Utils.Lens

A cut-down implementation of lenses, with names taken from Edward Kmett's lens package.

Documentation

type Lens' i o = forall f. Functor f => (i -> f i) -> o -> f o

Van Laarhoven style homogeneous lenses. Mnemoic: "Lens inner outer".

type LensGet i o = o -> i

type LensSet i o = i -> o -> o

type LensMap i o = (i -> i) -> o -> o

key :: Ord k => k -> Lens' (Maybe v) (Map k v)

(.=) :: MonadState o m => Lens' i o -> i -> m () infix 4

Write a part of the state.

over :: Lens' i o -> LensMap i o

Modify inner part i of structure o using a function i -> i.

set :: Lens' i o -> LensSet i o

Set inner part i of structure o as designated by Lens' i o.

lFst :: Lens' a (a, b)

lSnd :: Lens' b (a, b)

(^.) :: o -> Lens' i o -> i infixl 8

Get inner part i of structure o as designated by Lens' i o.

focus :: Monad m => Lens' i o -> StateT i m a -> StateT o m a

Focus on a part of the state for a stateful computation.

use :: MonadState o m => Lens' i o -> m i

Read a part of the state.

(%=) :: MonadState o m => Lens' i o -> (i -> i) -> m () infix 4

Modify a part of the state.

(%==) :: MonadState o m => Lens' i o -> (i -> m i) -> m () infix 4

Modify a part of the state monadically.

(%%=) :: MonadState o m => Lens' i o -> (i -> m (i, r)) -> m r infix 4

Modify a part of the state monadically, and return some result.

locallyState :: MonadState o m => Lens' i o -> (i -> i) -> m r -> m r

Modify a part of the state locally.

view :: MonadReader o m => Lens' i o -> m i

Ask for part of read-only state.

locally :: MonadReader o m => Lens' i o -> (i -> i) -> m a -> m a

Modify a part of the state in a subcomputation.

locally' :: ((o -> o) -> m a -> m a) -> Lens' i o -> (i -> i) -> m a -> m a

(<&>) :: Functor m => m a -> (a -> b) -> m b infixl 1

Infix version of for.