Air.Data.Record.SimpleLabel

Getter, setter and modifier types.

type Getter s x = s -> x

type Setter s x = x -> s -> s

type Modifier s x = (x -> x) -> s -> s

Label type.

data Point s x

newtype s :-> x

Constructors

Label (Point s x)

Instances

Category * (:->)

label :: Getter s x -> Setter s x -> s :-> x

get :: (s :-> x) -> s -> x

Get the getter function from a label.

set :: (s :-> x) -> x -> s -> s

Get the setter function from a label.

mod :: (s :-> x) -> (x -> x) -> s -> s

Get the modifier function from a label.

getM :: MonadState s m => (s :-> b) -> m b

Get a value out of state pointed to by the specified label.

setM :: MonadState s m => (s :-> b) -> b -> m ()

Set a value somewhere in state pointed to by the specified label.

modM :: MonadState s m => (s :-> b) -> (b -> b) -> m ()

Modify a value with a function somewhere in state pointed to by the specified label.

(=:) :: MonadState s m => (s :-> b) -> b -> m () infixr 7

Alias for setM that reads like an assignment.