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Edward Kmett committed Jun 28, 2011
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140 changes: 140 additions & 0 deletions Data/Lens/Common.hs
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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

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

newtype Lens a b = Lens { runLens :: a -> Store b a }

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

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

-- * Lens construction

-- | 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)

-- | build a lens out of an isomorphism
iso :: (a -> b) -> (b -> a) -> Lens a b
iso f g = Lens (store g . f)

infixr 0 ^$, ^$!

-- | functional getter
(^$), (^$!) :: Lens a b -> a -> b
Lens f ^$ a = pos (f a)
Lens f ^$! a = pos (f $! a)

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)

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

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

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

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)

infixr 4 ^/=, ^!/=
(^/=), (^!/=) :: Fractional b => Lens a b -> b -> a -> a
l ^/= r = l ^%= (/ r)
l ^!/= r = l ^!%= (/ r)

-- * Stock lenses

fstLens :: Lens (a,b) a
fstLens = Lens $ \(a,b) -> store (\ a' -> (a', b)) a

sndLens :: Lens (a,b) b
sndLens = Lens $ \(a,b) -> store (\ b' -> (a, b')) b

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)

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)

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)

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)
90 changes: 90 additions & 0 deletions Data/Lens/Lazy.hs
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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

import Control.Comonad.Trans.Store
import Control.Monad.Trans.State
import Control.Monad (liftM)
import Data.Functor.Identity
import Data.Lens.Common

-- * State actions

-- | 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 #-}

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)

infixr 4 ~=, !=

-- | 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)

infixr 4 %=, !%=

-- | 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')

infixr 4 %%=, !%%=

-- | 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')

infixr 4 +=, !+=, -=, !-=, *=, !*=

(+=), (!+=), (-=), (!-=), (*=), (!*=) :: (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)

infixr 4 //=, !/=

(//=), (!/=) :: (Monad m, Fractional b) => Lens a b -> b -> StateT a m b
f //= b = f %= (/ b)
f !/= b = f !%= (/ b)

infixr 4 &&=, !&&=, ||=, !||=

(&&=), (||=), (!&&=), (!||=) :: 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)

90 changes: 90 additions & 0 deletions Data/Lens/Strict.hs
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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

import Control.Comonad.Trans.Store
import Control.Monad.Trans.State.Strict
import Control.Monad (liftM)
import Data.Functor.Identity
import Data.Lens.Common

-- * State actions

-- | 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 #-}

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)

infixr 4 ~=, !=

-- | 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)

infixr 4 %=, !%=

-- | 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')

infixr 4 %%=, !%%=

-- | 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')

infixr 4 +=, !+=, -=, !-=, *=, !*=

(+=), (!+=), (-=), (!-=), (*=), (!*=) :: (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)

infixr 4 //=, !/=

(//=), (!/=) :: (Monad m, Fractional b) => Lens a b -> b -> StateT a m b
f //= b = f %= (/ b)
f !/= b = f !%= (/ b)

infixr 4 &&=, !&&=, ||=, !||=

(&&=), (||=), (!&&=), (!||=) :: 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)

30 changes: 30 additions & 0 deletions LICENSE
@@ -0,0 +1,30 @@
Copyright 2008-2011 Edward Kmett

All rights reserved.

Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions
are met:

1. Redistributions of source code must retain the above copyright
notice, this list of conditions and the following disclaimer.

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.

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.

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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