Copyright | (C) 2012-16 Edward Kmett |
---|---|
License | BSD-style (see the file LICENSE) |
Maintainer | Edward Kmett <ekmett@gmail.com> |
Stability | provisional |
Portability | Rank2Types |
Safe Haskell | Trustworthy |
Language | Haskell2010 |
Synopsis
- type family Magnified (m :: Type -> Type) :: Type -> Type -> Type
- class (Magnified m ~ Magnified n, MonadReader b m, MonadReader a n) => Magnify m n b a | m -> b, n -> a, m a -> n, n b -> m where
- class (MonadState s m, MonadState t n) => Zoom m n s t | m -> s, n -> t, m t -> n, n s -> m where
- type family Zoomed (m :: Type -> Type) :: Type -> Type -> Type
Documentation
type family Magnified (m :: Type -> Type) :: Type -> Type -> Type Source #
This type family is used by Magnify
to describe the common effect type.
Instances
type Magnified (IdentityT m) Source # | |
Defined in Control.Lens.Zoom | |
type Magnified (ReaderT b m) Source # | |
Defined in Control.Lens.Zoom | |
type Magnified ((->) b) Source # | |
type Magnified (RWST a w s m) Source # | |
Defined in Control.Lens.Zoom | |
type Magnified (RWST a w s m) Source # | |
Defined in Control.Lens.Zoom |
class (Magnified m ~ Magnified n, MonadReader b m, MonadReader a n) => Magnify m n b a | m -> b, n -> a, m a -> n, n b -> m where Source #
This class allows us to use magnify
part of the environment, changing the environment supplied by
many different Monad
transformers. Unlike zoom
this can change the environment of a deeply nested Monad
transformer.
Also, unlike zoom
, this can be used with any valid Getter
, but cannot be used with a Traversal
or Fold
.
magnify :: ((Functor (Magnified m c), Contravariant (Magnified m c)) => LensLike' (Magnified m c) a b) -> m c -> n c infixr 2 Source #
Run a monadic action in a larger environment than it was defined in, using a Getter
.
This acts like local
, but can in many cases change the type of the environment as well.
This is commonly used to lift actions in a simpler Reader
Monad
into a Monad
with a larger environment type.
This can be used to edit pretty much any Monad
transformer stack with an environment in it:
>>>
(1,2) & magnify _2 (+1)
3
>>>
flip Reader.runReader (1,2) $ magnify _1 Reader.ask
1
>>>
flip Reader.runReader (1,2,[10..20]) $ magnify (_3._tail) Reader.ask
[11,12,13,14,15,16,17,18,19,20]
The type can be read as
magnify :: LensLike' (Magnified m c) a b -> m c -> n c
but the higher-rank constraints make it easier to apply magnify
to a
Getter
in highly-polymorphic code.
magnify
::Getter
s a -> (a -> r) -> s -> rmagnify
::Monoid
r =>Fold
s a -> (a -> r) -> s -> r
magnify
::Monoid
w =>Getter
s t ->RWS
t w st c ->RWS
s w st cmagnify
:: (Monoid
w,Monoid
c) =>Fold
s a ->RWS
a w st c ->RWS
s w st c ...
Instances
Magnify m n b a => Magnify (IdentityT m) (IdentityT n) b a Source # | |
Monad m => Magnify (ReaderT b m) (ReaderT a m) b a Source # | |
Magnify ((->) b) ((->) a) b a Source # |
|
Defined in Control.Lens.Zoom | |
(Monad m, Monoid w) => Magnify (RWST b w s m) (RWST a w s m) b a Source # | |
(Monad m, Monoid w) => Magnify (RWST b w s m) (RWST a w s m) b a Source # | |
class (MonadState s m, MonadState t n) => Zoom m n s t | m -> s, n -> t, m t -> n, n s -> m where Source #
This class allows us to use zoom
in, changing the State
supplied by
many different Monad
transformers, potentially quite
deep in a Monad
transformer stack.
zoom :: LensLike' (Zoomed m c) t s -> m c -> n c infixr 2 Source #
Run a monadic action in a larger State
than it was defined in,
using a Lens'
or Traversal'
.
This is commonly used to lift actions in a simpler State
Monad
into a State
Monad
with a larger State
type.
When applied to a Traversal'
over
multiple values, the actions for each target are executed sequentially
and the results are aggregated.
This can be used to edit pretty much any Monad
transformer stack with a State
in it!
>>>
flip State.evalState (a,b) $ zoom _1 $ use id
a
>>>
flip State.execState (a,b) $ zoom _1 $ id .= c
(c,b)
>>>
flip State.execState [(a,b),(c,d)] $ zoom traverse $ _2 %= f
[(a,f b),(c,f d)]
>>>
flip State.runState [(a,b),(c,d)] $ zoom traverse $ _2 <%= f
(f b <> f d <> mempty,[(a,f b),(c,f d)])
>>>
flip State.evalState (a,b) $ zoom both (use id)
a <> b
zoom
::Monad
m =>Lens'
s t ->StateT
t m a ->StateT
s m azoom
:: (Monad
m,Monoid
c) =>Traversal'
s t ->StateT
t m c ->StateT
s m czoom
:: (Monad
m,Monoid
w) =>Lens'
s t ->RWST
r w t m c ->RWST
r w s m czoom
:: (Monad
m,Monoid
w,Monoid
c) =>Traversal'
s t ->RWST
r w t m c ->RWST
r w s m czoom
:: (Monad
m,Monoid
w,Error
e) =>Lens'
s t ->ErrorT
e (RWST
r w t m) c ->ErrorT
e (RWST
r w s m) czoom
:: (Monad
m,Monoid
w,Monoid
c,Error
e) =>Traversal'
s t ->ErrorT
e (RWST
r w t m) c ->ErrorT
e (RWST
r w s m) c ...
Instances
Zoom m n s t => Zoom (ListT m) (ListT n) s t Source # | |
Zoom m n s t => Zoom (MaybeT m) (MaybeT n) s t Source # | |
(Functor f, Zoom m n s t) => Zoom (FreeT f m) (FreeT f n) s t Source # | |
(Error e, Zoom m n s t) => Zoom (ErrorT e m) (ErrorT e n) s t Source # | |
Zoom m n s t => Zoom (ExceptT e m) (ExceptT e n) s t Source # | |
Zoom m n s t => Zoom (IdentityT m) (IdentityT n) s t Source # | |
Zoom m n s t => Zoom (ReaderT e m) (ReaderT e n) s t Source # | |
Monad z => Zoom (StateT s z) (StateT t z) s t Source # | |
Monad z => Zoom (StateT s z) (StateT t z) s t Source # | |
(Monoid w, Zoom m n s t) => Zoom (WriterT w m) (WriterT w n) s t Source # | |
(Monoid w, Zoom m n s t) => Zoom (WriterT w m) (WriterT w n) s t Source # | |
(Monoid w, Monad z) => Zoom (RWST r w s z) (RWST r w t z) s t Source # | |
(Monoid w, Monad z) => Zoom (RWST r w s z) (RWST r w t z) s t Source # | |
type family Zoomed (m :: Type -> Type) :: Type -> Type -> Type Source #
This type family is used by Zoom
to describe the common effect type.
Instances
type Zoomed (ListT m) Source # | |
Defined in Control.Lens.Zoom | |
type Zoomed (MaybeT m) Source # | |
Defined in Control.Lens.Zoom | |
type Zoomed (FreeT f m) Source # | |
Defined in Control.Lens.Zoom | |
type Zoomed (ErrorT e m) Source # | |
Defined in Control.Lens.Zoom | |
type Zoomed (ExceptT e m) Source # | |
Defined in Control.Lens.Zoom | |
type Zoomed (IdentityT m) Source # | |
Defined in Control.Lens.Zoom | |
type Zoomed (ReaderT e m) Source # | |
Defined in Control.Lens.Zoom | |
type Zoomed (StateT s z) Source # | |
Defined in Control.Lens.Zoom | |
type Zoomed (StateT s z) Source # | |
Defined in Control.Lens.Zoom | |
type Zoomed (WriterT w m) Source # | |
Defined in Control.Lens.Zoom | |
type Zoomed (WriterT w m) Source # | |
Defined in Control.Lens.Zoom | |
type Zoomed (RWST r w s z) Source # | |
Defined in Control.Lens.Zoom | |
type Zoomed (RWST r w s z) Source # | |
Defined in Control.Lens.Zoom |