CHR.Data.Lens.FCLabels

Minimal redefine + re-export of a lens package, fclabels

Documentation

type (:->) f o = Lens Total f o

Total monomorphic lens.

type Lens a b = a :-> b

Access

(^*) :: (a :-> b) -> (b :-> c) -> a :-> c infixl 9

composition with a flipped reading

(^.) :: a -> (a :-> b) -> b infixl 8

functional getter, which acts like a field accessor

(^=) :: (a :-> b) -> b -> a -> a infixr 4

functional setter, which acts like a field assigner

(^$=) :: (a :-> b) -> (b -> b) -> a -> a infixr 4

functional modify

getL :: (f :-> a) -> f -> a

Alias for get to avoid conflict with state get; not happy choice because of getl

(=.) :: MonadState f m => Lens ((->) LiftedRep LiftedRep) f o -> (o -> o) -> m () infixr 2

Alias for modify that reads more or less like an assignment.

(=:) :: MonadState f m => Lens ((->) LiftedRep LiftedRep) f o -> o -> m () infixr 2

Alias for puts that reads like an assignment.

(=$:) :: MonadState f m => (f :-> o) -> (o -> o) -> m () infixr 4

monadic modify & set

modifyAndGet :: MonadState f m => Lens ((->) LiftedRep LiftedRep) f o -> (o -> (a, o)) -> m a

Modify a value with a function somewhere in the state, pointed to by the specified lens. Additionally return a separate value based on the modification.

(=$^:) :: MonadState f m => (f :-> o) -> (o -> (a, o)) -> m a infixr 4

monadic modify & set & get

modL :: MonadState f m => (f :-> o) -> (o -> (a, o)) -> m a

monadic modify & set & get

getl :: MonadState f m => (f :-> o) -> m o

Alias for gets avoiding conflict with MonadState

Misc

focus :: (MonadState a m, MonadState b m) => (a :-> b) -> m c -> m c

Zoom state in on substructure. This regretfully does not really work, because of MonadState fundep.

mkLabel :: Name -> Q [Dec]

Derive labels including type signatures for all the record selectors in a single datatype. The types will be polymorphic and can be used in an arbitrary context.

Tuple accessors

fstl :: ArrowApply arr => Lens arr ((a, b) -> (o, b)) (a -> o)

sndl :: ArrowApply arr => Lens arr ((a, b) -> (a, o)) (b -> o)

fst3l :: ArrowApply arr => Lens arr ((a, b, c) -> (o, b, c)) (a -> o)

snd3l :: ArrowApply arr => Lens arr ((a, b, c) -> (a, o, c)) (b -> o)

trd3l :: ArrowApply arr => Lens arr ((a, b, c) -> (a, b, o)) (c -> o)

Wrappers

isoMb :: String -> (f :-> Maybe o) -> f :-> o

Wrapper around a Maybe with an embedded panic in case of Nothing, with a panic message

isoMbWithDefault :: o -> (f :-> Maybe o) -> f :-> o

Wrapper around a Maybe with a default in case of Nothing