| Copyright | (C) 2012-16 Edward Kmett Michael Sloan |
|---|---|
| License | BSD-style (see the file LICENSE) |
| Maintainer | Edward Kmett <ekmett@gmail.com> |
| Stability | experimental |
| Portability | Rank2, MPTCs, fundeps |
| Safe Haskell | Trustworthy |
| Language | Haskell2010 |
Control.Lens.Wrapped
Description
The
Wrapped
class provides similar functionality as
Control.Newtype
,
from the
newtype
package, but in a more convenient and efficient form.
There are a few functions from
newtype
that are not provided here, because
they can be done with the
Iso
directly:
Control.Newtype.overSumf ≡_UnwrappingSum%~f Control.Newtype.underSumf ≡_WrappingSum%~f Control.Newtype.overFSumf ≡mapping(_UnwrappingSum)%~f Control.Newtype.underFSumf ≡mapping(_WrappingSum)%~f
under
can also be used with
_Unwrapping
to provide the equivalent of
Control.Newtype.under
. Also, most use cases don't need full polymorphism,
so only the single constructor
_Wrapping
functions would be needed.
These equivalences aren't 100% honest, because
newtype
's operators
need to rely on two
Newtype
constraints. This means that the wrapper used
for the output is not necessarily the same as the input.
Synopsis
- class Wrapped s where
- _Unwrapped' :: Wrapped s => Iso' ( Unwrapped s) s
- _Wrapping' :: Wrapped s => ( Unwrapped s -> s) -> Iso' s ( Unwrapped s)
- _Unwrapping' :: Wrapped s => ( Unwrapped s -> s) -> Iso' ( Unwrapped s) s
- class Wrapped s => Rewrapped (s :: *) (t :: *)
- class ( Rewrapped s t, Rewrapped t s) => Rewrapping s t
- _Wrapped :: Rewrapping s t => Iso s t ( Unwrapped s) ( Unwrapped t)
- _Unwrapped :: Rewrapping s t => Iso ( Unwrapped t) ( Unwrapped s) t s
- _Wrapping :: Rewrapping s t => ( Unwrapped s -> s) -> Iso s t ( Unwrapped s) ( Unwrapped t)
- _Unwrapping :: Rewrapping s t => ( Unwrapped s -> s) -> Iso ( Unwrapped t) ( Unwrapped s) t s
- op :: Wrapped s => ( Unwrapped s -> s) -> s -> Unwrapped s
- ala :: ( Functor f, Rewrapping s t) => ( Unwrapped s -> s) -> (( Unwrapped t -> t) -> f s) -> f ( Unwrapped s)
- alaf :: ( Functor f, Functor g, Rewrapping s t) => ( Unwrapped s -> s) -> (f t -> g s) -> f ( Unwrapped t) -> g ( Unwrapped s)
- pattern Wrapped :: Rewrapped s s => Unwrapped s -> s
- pattern Unwrapped :: Rewrapped t t => t -> Unwrapped t
- _GWrapped' :: ( Generic s, D1 d ( C1 c ( S1 s' ( Rec0 a))) ~ Rep s, Unwrapped s ~ GUnwrapped ( Rep s)) => Iso' s ( Unwrapped s)
Wrapping and Unwrapping monomorphically
class Wrapped s where Source #
Wrapped
provides isomorphisms to wrap and unwrap newtypes or
data types with one constructor.
Minimal complete definition
Nothing
Methods
_Wrapped' :: Iso' s ( Unwrapped s) Source #
An isomorphism between
s
and
a
.
If your type has a
Generic
instance,
_Wrapped'
will default to
_GWrapped'
,
and you can choose to not override it with your own definition.
Instances
_Wrapping' :: Wrapped s => ( Unwrapped s -> s) -> Iso' s ( Unwrapped s) Source #
This is a convenient version of
_Wrapped
with an argument that's ignored.
The user supplied function is ignored , merely its type is used.
_Unwrapping' :: Wrapped s => ( Unwrapped s -> s) -> Iso' ( Unwrapped s) s Source #
This is a convenient version of
_Wrapped
with an argument that's ignored.
The user supplied function is ignored , merely its type is used.
Wrapping and unwrapping polymorphically
class Wrapped s => Rewrapped (s :: *) (t :: *) Source #
Instances
class ( Rewrapped s t, Rewrapped t s) => Rewrapping s t Source #
Instances
| ( Rewrapped s t, Rewrapped t s) => Rewrapping s t Source # | |
|
Defined in Control.Lens.Wrapped |
|
_Wrapped :: Rewrapping s t => Iso s t ( Unwrapped s) ( Unwrapped t) Source #
Work under a newtype wrapper.
>>>Const "hello" & _Wrapped %~ Prelude.length & getConst5
_Wrapped≡from_Unwrapped_Unwrapped≡from_Wrapped
_Unwrapped :: Rewrapping s t => Iso ( Unwrapped t) ( Unwrapped s) t s Source #
_Wrapping :: Rewrapping s t => ( Unwrapped s -> s) -> Iso s t ( Unwrapped s) ( Unwrapped t) Source #
This is a convenient version of
_Wrapped
with an argument that's ignored.
The user supplied function is ignored , merely its types are used.
_Unwrapping :: Rewrapping s t => ( Unwrapped s -> s) -> Iso ( Unwrapped t) ( Unwrapped s) t s Source #
This is a convenient version of
_Unwrapped
with an argument that's ignored.
The user supplied function is ignored , merely its types are used.
Operations
ala :: ( Functor f, Rewrapping s t) => ( Unwrapped s -> s) -> (( Unwrapped t -> t) -> f s) -> f ( Unwrapped s) Source #
This combinator is based on
ala
from Conor McBride's work on Epigram.
As with
_Wrapping
, the user supplied function for the newtype is
ignored
.
>>>ala Sum foldMap [1,2,3,4]10
>>>ala All foldMap [True,True]True
>>>ala All foldMap [True,False]False
>>>ala Any foldMap [False,False]False
>>>ala Any foldMap [True,False]True
>>>ala Product foldMap [1,2,3,4]24
You may want to think of this combinator as having the following, simpler, type.
ala :: Rewrapping s t => (Unwrapped s -> s) -> ((Unwrapped t -> t) -> e -> s) -> e -> Unwrapped s
alaf :: ( Functor f, Functor g, Rewrapping s t) => ( Unwrapped s -> s) -> (f t -> g s) -> f ( Unwrapped t) -> g ( Unwrapped s) Source #
This combinator is based on
ala'
from Conor McBride's work on Epigram.
As with
_Wrapping
, the user supplied function for the newtype is
ignored
.
alaf :: Rewrapping s t => (Unwrapped s -> s) -> ((r -> t) -> e -> s) -> (r -> Unwrapped t) -> e -> Unwrapped s
>>>alaf Sum foldMap Prelude.length ["hello","world"]10