Agda-2.5.1: A dependently typed functional programming language and proof assistant

Safe HaskellSafe
LanguageHaskell98

Agda.Utils.Lens

Contents

Description

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

Synopsis

Type-preserving lenses.

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

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

Elementary lens operations.

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

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

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

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

over :: Lens' i o -> (i -> i) -> o -> o Source

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

State accessors and modifiers.

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

Read a part of the state.

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

Write a part of the state.

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

Modify a part of the state.

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

Modify a part of the state monadically.

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

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

Read-only state accessors and modifiers.

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

Ask for part of read-only state.

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

Modify a part of the state in a subcomputation.

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

(<&>) :: Functor m => m a -> (a -> b) -> m b infix 4 Source

Infix version of for.