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module Data.Lens.Common | ||
( Lens(..) | ||
-- * Lens construction | ||
, lens -- build a lens from a getter and setter | ||
, iso -- build a lens from an isomorphism | ||
-- * Functional API | ||
, (^$), (^$!) -- getter -- :: Lens a b -> a -> b | ||
, (^.), (^!) -- getter -- :: a -> Lens a b -> b | ||
, (^=), (^!=) -- setter -- :: Lens a b -> b -> (a -> a) | ||
, (^%=), (^!%=) -- modify -- :: Lens a b -> (b -> b) -> (a -> a) | ||
, (^%%=) -- modify -- :: Functor f => Lens a b -> (b -> f b) -> a -> f a | ||
-- * Pseudo-imperatives | ||
, (^+=), (^!+=) -- addition | ||
, (^-=), (^!-=) -- subtraction | ||
, (^*=), (^!*=) -- multiplication | ||
, (^/=), (^!/=) -- division | ||
-- * Stock lenses | ||
, fstLens | ||
, sndLens | ||
, mapLens | ||
, intMapLens | ||
, setLens | ||
, intSetLens | ||
) where | ||
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import Control.Applicative | ||
import Control.Comonad.Trans.Store | ||
import Control.Category | ||
import Data.Functor.Identity | ||
import Data.Functor.Apply | ||
import Data.Semigroupoid | ||
import Prelude hiding ((.), id) | ||
import Data.IntMap (IntMap) | ||
import qualified Data.Map as Map | ||
import Data.Set (Set) | ||
import qualified Data.IntMap as IntMap | ||
import Data.Map (Map) | ||
import qualified Data.Set as Set | ||
import Data.IntSet (IntSet) | ||
import qualified Data.IntSet as IntSet | ||
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newtype Lens a b = Lens { runLens :: a -> Store b a } | ||
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instance Semigroupoid Lens where | ||
Lens f `o` Lens g = Lens $ \a -> case g a of | ||
StoreT wba b -> case f b of | ||
StoreT wcb c -> StoreT ((.) <$> wba <.> wcb) c | ||
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instance Category Lens where | ||
id = Lens $ StoreT (pure id) | ||
Lens f . Lens g = Lens $ \a -> case g a of | ||
StoreT wba b -> case f b of | ||
StoreT wcb c -> StoreT ((.) <$> wba <*> wcb) c | ||
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-- * Lens construction | ||
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-- | build a lens out of a getter and setter | ||
lens :: (a -> b) -> (b -> a -> a) -> Lens a b | ||
lens get set = Lens $ \a -> store (\b -> set b a) (get a) | ||
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-- | build a lens out of an isomorphism | ||
iso :: (a -> b) -> (b -> a) -> Lens a b | ||
iso f g = Lens (store g . f) | ||
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infixr 0 ^$, ^$! | ||
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-- | functional getter | ||
(^$), (^$!) :: Lens a b -> a -> b | ||
Lens f ^$ a = pos (f a) | ||
Lens f ^$! a = pos (f $! a) | ||
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infixr 9 ^., ^! | ||
-- | functional getter, which acts like a field accessor | ||
(^.), (^!) :: a -> Lens a b -> b | ||
a ^. Lens f = pos (f a) | ||
a ^! Lens f = pos (f $! a) | ||
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infixr 4 ^=, ^!= | ||
-- | functional setter | ||
(^=), (^!=) :: Lens a b -> b -> a -> a | ||
Lens f ^= b = peek b . f | ||
Lens f ^!= b = \a -> case f a of | ||
StoreT (Identity g) _ -> g $! b | ||
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infixr 4 ^%=, ^!%= | ||
-- | functional modify | ||
(^%=), (^!%=) :: Lens a b -> (b -> b) -> a -> a | ||
Lens f ^%= g = peeks g . f | ||
Lens f ^!%= g = \a -> case f a of | ||
StoreT (Identity h) b -> h $! g b | ||
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infixr 4 ^%%= | ||
-- | functorial modify | ||
(^%%=) :: Functor f => Lens a b -> (b -> f b) -> a -> f a | ||
Lens f ^%%= g = \a -> case f a of | ||
StoreT (Identity h) b -> h <$> g b | ||
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infixr 4 ^+=, ^!+=, ^-=, ^!-=, ^*=, ^!*= | ||
(^+=), (^!+=), (^-=), (^!-=), (^*=), (^!*=) :: Num b => Lens a b -> b -> a -> a | ||
l ^+= n = l ^%= (+ n) | ||
l ^-= n = l ^%= subtract n | ||
l ^*= n = l ^%= (* n) | ||
l ^!+= n = l ^!%= (+ n) | ||
l ^!-= n = l ^!%= subtract n | ||
l ^!*= n = l ^!%= (* n) | ||
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infixr 4 ^/=, ^!/= | ||
(^/=), (^!/=) :: Fractional b => Lens a b -> b -> a -> a | ||
l ^/= r = l ^%= (/ r) | ||
l ^!/= r = l ^!%= (/ r) | ||
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-- * Stock lenses | ||
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fstLens :: Lens (a,b) a | ||
fstLens = Lens $ \(a,b) -> store (\ a' -> (a', b)) a | ||
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sndLens :: Lens (a,b) b | ||
sndLens = Lens $ \(a,b) -> store (\ b' -> (a, b')) b | ||
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mapLens :: Ord k => k -> Lens (Map k v) (Maybe v) | ||
mapLens k = Lens $ \m -> store (\mv -> case mv of | ||
Nothing -> Map.delete k m | ||
Just v' -> Map.insert k v' m | ||
) (Map.lookup k m) | ||
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intMapLens :: Int -> Lens (IntMap v) (Maybe v) | ||
intMapLens k = Lens $ \m -> store (\mv -> case mv of | ||
Nothing -> IntMap.delete k m | ||
Just v' -> IntMap.insert k v' m | ||
) (IntMap.lookup k m) | ||
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setLens :: Ord k => k -> Lens (Set k) Bool | ||
setLens k = Lens $ \m -> store (\mv -> | ||
if mv then Set.delete k m else Set.insert k m | ||
) (Set.member k m) | ||
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intSetLens :: Int -> Lens IntSet Bool | ||
intSetLens k = Lens $ \m -> store (\mv -> | ||
if mv then IntSet.delete k m else IntSet.insert k m | ||
) (IntSet.member k m) |
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module Data.Lens.Lazy | ||
( module Data.Lens.Common | ||
-- * State API | ||
, access -- getter -- :: Monad m => Lens a b -> StateT a m b | ||
, (~=), (!=) -- setter -- :: Monad m => Lens a b -> b -> StateT a m b | ||
, (%=), (!%=) -- modify -- :: Monad m => Lens a b -> (b -> b) -> StateT a m b | ||
, (%%=), (!%%=) -- modify -- :: Monad m => Lens a b -> (b -> (c, b)) -> StateT a m c | ||
, (+=), (!+=) -- modify -- :: (Monad m, Num b) => Lens a b -> b -> StateT a m b | ||
, (-=), (!-=) -- modify -- :: (Monad m, Num b) => Lens a b -> b -> StateT a m b | ||
, (*=), (!*=) -- modify -- :: (Monad m, Num b) => Lens a b -> b -> StateT a m b | ||
, (//=), (!/=) -- modify -- :: (Monad m, Fractional b) => Lens a b -> b -> StateT a m b | ||
, (&&=), (!&&=) -- modify -- :: Monad m => Lens a Bool -> Bool -> StateT a m Bool | ||
, (||=), (!||=) -- modify -- :: Monad m => Lens a Bool -> Bool -> StateT a m Bool | ||
, focus -- modify -- :: Monad m => Lens a b -> StateT m b c -> StateT m a c | ||
) where | ||
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import Control.Comonad.Trans.Store | ||
import Control.Monad.Trans.State | ||
import Control.Monad (liftM) | ||
import Data.Functor.Identity | ||
import Data.Lens.Common | ||
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-- * State actions | ||
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-- | get the value of a lens into state | ||
access :: Monad m => Lens a b -> StateT a m b | ||
access (Lens f) = gets (pos . f) | ||
{-# INLINE access #-} | ||
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focus :: Monad m => Lens a b -> StateT b m c -> StateT a m c | ||
focus (Lens f) (StateT g) = StateT $ \a -> case f a of | ||
StoreT (Identity h) b -> liftM (\(c, b') -> (c, h b')) (g b) | ||
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infixr 4 ~=, != | ||
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-- | set a value using a lens into state | ||
(~=), (!=) :: Monad m => Lens a b -> b -> StateT a m b | ||
Lens f ~= b = StateT $ \a -> let c = peek b (f a) in | ||
return (b, c) | ||
Lens f != b = StateT $ \a -> case f a of | ||
StoreT (Identity h) _ -> let c = h $! b in | ||
return (b, c) | ||
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infixr 4 %=, !%= | ||
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-- | infix modification a value through a lens into state | ||
(%=), (!%=) :: Monad m => Lens a b -> (b -> b) -> StateT a m b | ||
Lens f %= g = StateT $ \a -> case f a of | ||
StoreT (Identity h) b -> let b' = g b in | ||
return (b', h b') | ||
Lens f !%= g = StateT $ \a -> case f a of | ||
StoreT (Identity h) b -> let b' = g b in | ||
b' `seq` return (b', h b') | ||
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infixr 4 %%=, !%%= | ||
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-- | infix modification of a value through a lens into state | ||
-- with a supplemental response | ||
(%%=), (!%%=) :: Monad m => Lens a b -> (b -> (c, b)) -> StateT a m c | ||
Lens f %%= g = StateT $ \a -> case f a of | ||
StoreT (Identity h) b -> case g b of | ||
(c, b') -> return (c, h b') | ||
Lens f !%%= g = StateT $ \a -> case f a of | ||
StoreT (Identity h) b -> case g b of | ||
(c, b') -> return (c, h $! b') | ||
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infixr 4 +=, !+=, -=, !-=, *=, !*= | ||
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(+=), (!+=), (-=), (!-=), (*=), (!*=) :: (Monad m, Num b) => Lens a b -> b -> StateT a m b | ||
f += b = f %= (+ b) | ||
f -= b = f %= subtract b | ||
f *= b = f %= (* b) | ||
f !+= b = f !%= (+ b) | ||
f !-= b = f !%= subtract b | ||
f !*= b = f !%= (* b) | ||
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infixr 4 //=, !/= | ||
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(//=), (!/=) :: (Monad m, Fractional b) => Lens a b -> b -> StateT a m b | ||
f //= b = f %= (/ b) | ||
f !/= b = f !%= (/ b) | ||
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infixr 4 &&=, !&&=, ||=, !||= | ||
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(&&=), (||=), (!&&=), (!||=) :: Monad m => Lens a Bool -> Bool -> StateT a m Bool | ||
f &&= b = f %= (&& b) | ||
f ||= b = f %= (|| b) | ||
f !&&= b = f !%= (&& b) | ||
f !||= b = f !%= (|| b) | ||
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module Data.Lens.Strict | ||
( module Data.Lens.Common | ||
-- * State API | ||
, access -- getter -- :: Monad m => Lens a b -> StateT a m b | ||
, (~=), (!=) -- setter -- :: Monad m => Lens a b -> b -> StateT a m b | ||
, (%=), (!%=) -- modify -- :: Monad m => Lens a b -> (b -> b) -> StateT a m b | ||
, (%%=), (!%%=) -- modify -- :: Monad m => Lens a b -> (b -> (c, b)) -> StateT a m c | ||
, (+=), (!+=) -- modify -- :: (Monad m, Num b) => Lens a b -> b -> StateT a m b | ||
, (-=), (!-=) -- modify -- :: (Monad m, Num b) => Lens a b -> b -> StateT a m b | ||
, (*=), (!*=) -- modify -- :: (Monad m, Num b) => Lens a b -> b -> StateT a m b | ||
, (//=), (!/=) -- modify -- :: (Monad m, Fractional b) => Lens a b -> b -> StateT a m b | ||
, (&&=), (!&&=) -- modify -- :: Monad m => Lens a Bool -> Bool -> StateT a m Bool | ||
, (||=), (!||=) -- modify -- :: Monad m => Lens a Bool -> Bool -> StateT a m Bool | ||
, focus -- modify -- :: Monad m => Lens a b -> StateT m b c -> StateT m a c | ||
) where | ||
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import Control.Comonad.Trans.Store | ||
import Control.Monad.Trans.State.Strict | ||
import Control.Monad (liftM) | ||
import Data.Functor.Identity | ||
import Data.Lens.Common | ||
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-- * State actions | ||
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-- | get the value of a lens into state | ||
access :: Monad m => Lens a b -> StateT a m b | ||
access (Lens f) = gets (pos . f) | ||
{-# INLINE access #-} | ||
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focus :: Monad m => Lens a b -> StateT b m c -> StateT a m c | ||
focus (Lens f) (StateT g) = StateT $ \a -> case f a of | ||
StoreT (Identity h) b -> liftM (\(c, b') -> (c, h b')) (g b) | ||
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infixr 4 ~=, != | ||
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-- | set a value using a lens into state | ||
(~=), (!=) :: Monad m => Lens a b -> b -> StateT a m b | ||
Lens f ~= b = StateT $ \a -> let c = peek b (f a) in | ||
return (b, c) | ||
Lens f != b = StateT $ \a -> case f a of | ||
StoreT (Identity h) _ -> let c = h $! b in | ||
return (b, c) | ||
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infixr 4 %=, !%= | ||
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-- | infix modification a value through a lens into state | ||
(%=), (!%=) :: Monad m => Lens a b -> (b -> b) -> StateT a m b | ||
Lens f %= g = StateT $ \a -> case f a of | ||
StoreT (Identity h) b -> let b' = g b in | ||
return (b', h b') | ||
Lens f !%= g = StateT $ \a -> case f a of | ||
StoreT (Identity h) b -> let b' = g b in | ||
b' `seq` return (b', h b') | ||
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infixr 4 %%=, !%%= | ||
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-- | infix modification of a value through a lens into state | ||
-- with a supplemental response | ||
(%%=), (!%%=) :: Monad m => Lens a b -> (b -> (c, b)) -> StateT a m c | ||
Lens f %%= g = StateT $ \a -> case f a of | ||
StoreT (Identity h) b -> case g b of | ||
(c, b') -> return (c, h b') | ||
Lens f !%%= g = StateT $ \a -> case f a of | ||
StoreT (Identity h) b -> case g b of | ||
(c, b') -> return (c, h $! b') | ||
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infixr 4 +=, !+=, -=, !-=, *=, !*= | ||
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(+=), (!+=), (-=), (!-=), (*=), (!*=) :: (Monad m, Num b) => Lens a b -> b -> StateT a m b | ||
f += b = f %= (+ b) | ||
f -= b = f %= subtract b | ||
f *= b = f %= (* b) | ||
f !+= b = f !%= (+ b) | ||
f !-= b = f !%= subtract b | ||
f !*= b = f !%= (* b) | ||
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infixr 4 //=, !/= | ||
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(//=), (!/=) :: (Monad m, Fractional b) => Lens a b -> b -> StateT a m b | ||
f //= b = f %= (/ b) | ||
f !/= b = f !%= (/ b) | ||
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infixr 4 &&=, !&&=, ||=, !||= | ||
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(&&=), (||=), (!&&=), (!||=) :: Monad m => Lens a Bool -> Bool -> StateT a m Bool | ||
f &&= b = f %= (&& b) | ||
f ||= b = f %= (|| b) | ||
f !&&= b = f !%= (&& b) | ||
f !||= b = f !%= (|| b) | ||
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Copyright 2008-2011 Edward Kmett | ||
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All rights reserved. | ||
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Redistribution and use in source and binary forms, with or without | ||
modification, are permitted provided that the following conditions | ||
are met: | ||
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1. Redistributions of source code must retain the above copyright | ||
notice, this list of conditions and the following disclaimer. | ||
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2. Redistributions in binary form must reproduce the above copyright | ||
notice, this list of conditions and the following disclaimer in the | ||
documentation and/or other materials provided with the distribution. | ||
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3. Neither the name of the author nor the names of his contributors | ||
may be used to endorse or promote products derived from this software | ||
without specific prior written permission. | ||
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THIS SOFTWARE IS PROVIDED BY THE AUTHORS ``AS IS'' AND ANY EXPRESS OR | ||
IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED | ||
WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE | ||
DISCLAIMED. IN NO EVENT SHALL THE AUTHORS OR CONTRIBUTORS BE LIABLE FOR | ||
ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL | ||
DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS | ||
OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) | ||
HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, | ||
STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN | ||
ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE | ||
POSSIBILITY OF SUCH DAMAGE. |
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