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<pre><a name="line-1"></a><span class='hs-comment'>{-# LANGUAGE CPP #-}</span>
<a name="line-2"></a><span class='hs-comment'>{-# LANGUAGE Rank2Types #-}</span>
<a name="line-3"></a>
<a name="line-4"></a><span class='hs-cpp'>#ifndef MIN_VERSION_profunctors</span>
<a name="line-5"></a><span class='hs-cpp'>#define MIN_VERSION_profunctors(x,y,z) 1</span>
<a name="line-6"></a><span class='hs-cpp'>#endif</span>
<a name="line-7"></a>
<a name="line-8"></a><span class='hs-cpp'>#if __GLASGOW_HASKELL__ < 708 || !(MIN_VERSION_profunctors(4,4,0))</span>
<a name="line-9"></a><span class='hs-comment'>{-# LANGUAGE Trustworthy #-}</span>
<a name="line-10"></a><span class='hs-cpp'>#endif</span>
<a name="line-11"></a><span class='hs-comment'>-------------------------------------------------------------------------------</span>
<a name="line-12"></a><span class='hs-comment'>-- |</span>
<a name="line-13"></a><span class='hs-comment'>-- Module : Control.Lens.Review</span>
<a name="line-14"></a><span class='hs-comment'>-- Copyright : (C) 2012-15 Edward Kmett</span>
<a name="line-15"></a><span class='hs-comment'>-- License : BSD-style (see the file LICENSE)</span>
<a name="line-16"></a><span class='hs-comment'>-- Maintainer : Edward Kmett <ekmett@gmail.com></span>
<a name="line-17"></a><span class='hs-comment'>-- Stability : provisional</span>
<a name="line-18"></a><span class='hs-comment'>-- Portability : non-portable</span>
<a name="line-19"></a><span class='hs-comment'>--</span>
<a name="line-20"></a><span class='hs-comment'>-- A 'Review' is a type-restricted form of a 'Prism' that can only be used for</span>
<a name="line-21"></a><span class='hs-comment'>-- writing back via 're', 'review', 'reuse'.</span>
<a name="line-22"></a><span class='hs-comment'>-------------------------------------------------------------------------------</span>
<a name="line-23"></a><span class='hs-keyword'>module</span> <span class='hs-conid'>Control</span><span class='hs-varop'>.</span><span class='hs-conid'>Lens</span><span class='hs-varop'>.</span><span class='hs-conid'>Review</span>
<a name="line-24"></a> <span class='hs-layout'>(</span>
<a name="line-25"></a> <span class='hs-comment'>-- * Reviewing</span>
<a name="line-26"></a> <span class='hs-conid'>Review</span>
<a name="line-27"></a> <span class='hs-layout'>,</span> <span class='hs-conid'>AReview</span>
<a name="line-28"></a> <span class='hs-layout'>,</span> <span class='hs-varid'>unto</span>
<a name="line-29"></a> <span class='hs-layout'>,</span> <span class='hs-varid'>un</span>
<a name="line-30"></a> <span class='hs-layout'>,</span> <span class='hs-varid'>re</span>
<a name="line-31"></a> <span class='hs-layout'>,</span> <span class='hs-varid'>review</span><span class='hs-layout'>,</span> <span class='hs-varid'>reviews</span>
<a name="line-32"></a> <span class='hs-layout'>,</span> <span class='hs-varid'>reuse</span><span class='hs-layout'>,</span> <span class='hs-varid'>reuses</span>
<a name="line-33"></a> <span class='hs-layout'>,</span> <span class='hs-layout'>(</span> <span class='hs-cpp'>#</span> <span class='hs-layout'>)</span>
<a name="line-34"></a> <span class='hs-layout'>,</span> <span class='hs-conid'>Bifunctor</span><span class='hs-layout'>(</span><span class='hs-varid'>bimap</span><span class='hs-layout'>)</span>
<a name="line-35"></a> <span class='hs-layout'>,</span> <span class='hs-varid'>retagged</span>
<a name="line-36"></a> <span class='hs-layout'>,</span> <span class='hs-conid'>Reviewable</span>
<a name="line-37"></a> <span class='hs-layout'>)</span> <span class='hs-keyword'>where</span>
<a name="line-38"></a>
<a name="line-39"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Control</span><span class='hs-varop'>.</span><span class='hs-conid'>Monad</span><span class='hs-varop'>.</span><span class='hs-conid'>Reader</span> <span class='hs-keyword'>as</span> <span class='hs-conid'>Reader</span>
<a name="line-40"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Control</span><span class='hs-varop'>.</span><span class='hs-conid'>Monad</span><span class='hs-varop'>.</span><span class='hs-conid'>State</span> <span class='hs-keyword'>as</span> <span class='hs-conid'>State</span>
<a name="line-41"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Control</span><span class='hs-varop'>.</span><span class='hs-conid'>Lens</span><span class='hs-varop'>.</span><span class='hs-conid'>Getter</span>
<a name="line-42"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Control</span><span class='hs-varop'>.</span><span class='hs-conid'>Lens</span><span class='hs-varop'>.</span><span class='hs-conid'>Internal</span><span class='hs-varop'>.</span><span class='hs-conid'>Review</span>
<a name="line-43"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Control</span><span class='hs-varop'>.</span><span class='hs-conid'>Lens</span><span class='hs-varop'>.</span><span class='hs-conid'>Type</span>
<a name="line-44"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Data</span><span class='hs-varop'>.</span><span class='hs-conid'>Bifunctor</span>
<a name="line-45"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Data</span><span class='hs-varop'>.</span><span class='hs-conid'>Functor</span><span class='hs-varop'>.</span><span class='hs-conid'>Identity</span>
<a name="line-46"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Data</span><span class='hs-varop'>.</span><span class='hs-conid'>Profunctor</span>
<a name="line-47"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Data</span><span class='hs-varop'>.</span><span class='hs-conid'>Profunctor</span><span class='hs-varop'>.</span><span class='hs-conid'>Unsafe</span>
<a name="line-48"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Data</span><span class='hs-varop'>.</span><span class='hs-conid'>Tagged</span>
<a name="line-49"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Data</span><span class='hs-varop'>.</span><span class='hs-conid'>Void</span>
<a name="line-50"></a>
<a name="line-51"></a><span class='hs-comment'>-- $setup</span>
<a name="line-52"></a><span class='hs-comment'>-- >>> :set -XNoOverloadedStrings</span>
<a name="line-53"></a><span class='hs-comment'>-- >>> import Control.Lens</span>
<a name="line-54"></a><span class='hs-comment'>-- >>> import Numeric.Lens</span>
<a name="line-55"></a><span class='hs-comment'>-- >>> let isLeft (Left _) = True; isLeft _ = False</span>
<a name="line-56"></a><span class='hs-comment'>-- >>> let isRight (Right _) = True; isRight _ = False</span>
<a name="line-57"></a>
<a name="line-58"></a><span class='hs-keyword'>infixr</span> <span class='hs-num'>8</span> <span class='hs-cpp'>#</span>
<a name="line-59"></a>
<a name="line-60"></a><span class='hs-comment'>------------------------------------------------------------------------------</span>
<a name="line-61"></a><span class='hs-comment'>-- Review</span>
<a name="line-62"></a><span class='hs-comment'>------------------------------------------------------------------------------</span>
<a name="line-63"></a>
<a name="line-64"></a><a name="unto"></a><span class='hs-comment'>-- | An analogue of 'to' for 'review'.</span>
<a name="line-65"></a><span class='hs-comment'>--</span>
<a name="line-66"></a><span class='hs-comment'>-- @</span>
<a name="line-67"></a><span class='hs-comment'>-- 'unto' :: (b -> t) -> 'Review'' t b</span>
<a name="line-68"></a><span class='hs-comment'>-- @</span>
<a name="line-69"></a><span class='hs-comment'>--</span>
<a name="line-70"></a><span class='hs-comment'>-- @</span>
<a name="line-71"></a><span class='hs-comment'>-- 'unto' = 'un' . 'to'</span>
<a name="line-72"></a><span class='hs-comment'>-- @</span>
<a name="line-73"></a><span class='hs-definition'>unto</span> <span class='hs-keyglyph'>::</span> <span class='hs-layout'>(</span><span class='hs-conid'>Profunctor</span> <span class='hs-varid'>p</span><span class='hs-layout'>,</span> <span class='hs-conid'>Bifunctor</span> <span class='hs-varid'>p</span><span class='hs-layout'>,</span> <span class='hs-conid'>Functor</span> <span class='hs-varid'>f</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=></span> <span class='hs-layout'>(</span><span class='hs-varid'>b</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>t</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Optic</span> <span class='hs-varid'>p</span> <span class='hs-varid'>f</span> <span class='hs-varid'>s</span> <span class='hs-varid'>t</span> <span class='hs-varid'>a</span> <span class='hs-varid'>b</span>
<a name="line-74"></a><span class='hs-definition'>unto</span> <span class='hs-varid'>f</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>first</span> <span class='hs-varid'>absurd</span> <span class='hs-varop'>.</span> <span class='hs-varid'>lmap</span> <span class='hs-varid'>absurd</span> <span class='hs-varop'>.</span> <span class='hs-varid'>rmap</span> <span class='hs-layout'>(</span><span class='hs-varid'>fmap</span> <span class='hs-varid'>f</span><span class='hs-layout'>)</span>
<a name="line-75"></a><span class='hs-comment'>{-# INLINE unto #-}</span>
<a name="line-76"></a>
<a name="line-77"></a><a name="un"></a><span class='hs-comment'>-- | Turn a 'Getter' around to get a 'Review'</span>
<a name="line-78"></a><span class='hs-comment'>--</span>
<a name="line-79"></a><span class='hs-comment'>-- @</span>
<a name="line-80"></a><span class='hs-comment'>-- 'un' = 'unto' . 'view'</span>
<a name="line-81"></a><span class='hs-comment'>-- 'unto' = 'un' . 'to'</span>
<a name="line-82"></a><span class='hs-comment'>-- @</span>
<a name="line-83"></a><span class='hs-comment'>--</span>
<a name="line-84"></a><span class='hs-comment'>-- >>> un (to length) # [1,2,3]</span>
<a name="line-85"></a><span class='hs-comment'>-- 3</span>
<a name="line-86"></a><span class='hs-definition'>un</span> <span class='hs-keyglyph'>::</span> <span class='hs-layout'>(</span><span class='hs-conid'>Profunctor</span> <span class='hs-varid'>p</span><span class='hs-layout'>,</span> <span class='hs-conid'>Bifunctor</span> <span class='hs-varid'>p</span><span class='hs-layout'>,</span> <span class='hs-conid'>Functor</span> <span class='hs-varid'>f</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=></span> <span class='hs-conid'>Getting</span> <span class='hs-varid'>a</span> <span class='hs-varid'>s</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Optic'</span> <span class='hs-varid'>p</span> <span class='hs-varid'>f</span> <span class='hs-varid'>a</span> <span class='hs-varid'>s</span>
<a name="line-87"></a><span class='hs-definition'>un</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>unto</span> <span class='hs-varop'>.</span> <span class='hs-varid'>view</span>
<a name="line-88"></a>
<a name="line-89"></a><a name="re"></a><span class='hs-comment'>-- | Turn a 'Prism' or 'Control.Lens.Iso.Iso' around to build a 'Getter'.</span>
<a name="line-90"></a><span class='hs-comment'>--</span>
<a name="line-91"></a><span class='hs-comment'>-- If you have an 'Control.Lens.Iso.Iso', 'Control.Lens.Iso.from' is a more powerful version of this function</span>
<a name="line-92"></a><span class='hs-comment'>-- that will return an 'Control.Lens.Iso.Iso' instead of a mere 'Getter'.</span>
<a name="line-93"></a><span class='hs-comment'>--</span>
<a name="line-94"></a><span class='hs-comment'>-- >>> 5 ^.re _Left</span>
<a name="line-95"></a><span class='hs-comment'>-- Left 5</span>
<a name="line-96"></a><span class='hs-comment'>--</span>
<a name="line-97"></a><span class='hs-comment'>-- >>> 6 ^.re (_Left.unto succ)</span>
<a name="line-98"></a><span class='hs-comment'>-- Left 7</span>
<a name="line-99"></a><span class='hs-comment'>--</span>
<a name="line-100"></a><span class='hs-comment'>-- @</span>
<a name="line-101"></a><span class='hs-comment'>-- 'review' ≡ 'view' '.' 're'</span>
<a name="line-102"></a><span class='hs-comment'>-- 'reviews' ≡ 'views' '.' 're'</span>
<a name="line-103"></a><span class='hs-comment'>-- 'reuse' ≡ 'use' '.' 're'</span>
<a name="line-104"></a><span class='hs-comment'>-- 'reuses' ≡ 'uses' '.' 're'</span>
<a name="line-105"></a><span class='hs-comment'>-- @</span>
<a name="line-106"></a><span class='hs-comment'>--</span>
<a name="line-107"></a><span class='hs-comment'>-- @</span>
<a name="line-108"></a><span class='hs-comment'>-- 're' :: 'Prism' s t a b -> 'Getter' b t</span>
<a name="line-109"></a><span class='hs-comment'>-- 're' :: 'Iso' s t a b -> 'Getter' b t</span>
<a name="line-110"></a><span class='hs-comment'>-- @</span>
<a name="line-111"></a><span class='hs-definition'>re</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Contravariant</span> <span class='hs-varid'>f</span> <span class='hs-keyglyph'>=></span> <span class='hs-conid'>AReview</span> <span class='hs-varid'>t</span> <span class='hs-varid'>b</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>LensLike'</span> <span class='hs-varid'>f</span> <span class='hs-varid'>b</span> <span class='hs-varid'>t</span>
<a name="line-112"></a><span class='hs-definition'>re</span> <span class='hs-varid'>p</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>to</span> <span class='hs-layout'>(</span><span class='hs-varid'>runIdentity</span> <span class='hs-cpp'>#.</span> <span class='hs-varid'>unTagged</span> <span class='hs-cpp'>#.</span> <span class='hs-varid'>p</span> <span class='hs-varop'>.#</span> <span class='hs-conid'>Tagged</span> <span class='hs-varop'>.#</span> <span class='hs-conid'>Identity</span><span class='hs-layout'>)</span>
<a name="line-113"></a><span class='hs-comment'>{-# INLINE re #-}</span>
<a name="line-114"></a>
<a name="line-115"></a><a name="review"></a><span class='hs-comment'>-- | This can be used to turn an 'Control.Lens.Iso.Iso' or 'Prism' around and 'view' a value (or the current environment) through it the other way.</span>
<a name="line-116"></a><span class='hs-comment'>--</span>
<a name="line-117"></a><span class='hs-comment'>-- @</span>
<a name="line-118"></a><span class='hs-comment'>-- 'review' ≡ 'view' '.' 're'</span>
<a name="line-119"></a><span class='hs-comment'>-- 'review' . 'unto' ≡ 'id'</span>
<a name="line-120"></a><span class='hs-comment'>-- @</span>
<a name="line-121"></a><span class='hs-comment'>--</span>
<a name="line-122"></a><span class='hs-comment'>-- >>> review _Left "mustard"</span>
<a name="line-123"></a><span class='hs-comment'>-- Left "mustard"</span>
<a name="line-124"></a><span class='hs-comment'>--</span>
<a name="line-125"></a><span class='hs-comment'>-- >>> review (unto succ) 5</span>
<a name="line-126"></a><span class='hs-comment'>-- 6</span>
<a name="line-127"></a><span class='hs-comment'>--</span>
<a name="line-128"></a><span class='hs-comment'>-- Usually 'review' is used in the @(->)@ 'Monad' with a 'Prism' or 'Control.Lens.Iso.Iso', in which case it may be useful to think of</span>
<a name="line-129"></a><span class='hs-comment'>-- it as having one of these more restricted type signatures:</span>
<a name="line-130"></a><span class='hs-comment'>--</span>
<a name="line-131"></a><span class='hs-comment'>-- @</span>
<a name="line-132"></a><span class='hs-comment'>-- 'review' :: 'Iso'' s a -> a -> s</span>
<a name="line-133"></a><span class='hs-comment'>-- 'review' :: 'Prism'' s a -> a -> s</span>
<a name="line-134"></a><span class='hs-comment'>-- @</span>
<a name="line-135"></a><span class='hs-comment'>--</span>
<a name="line-136"></a><span class='hs-comment'>-- However, when working with a 'Monad' transformer stack, it is sometimes useful to be able to 'review' the current environment, in which case</span>
<a name="line-137"></a><span class='hs-comment'>-- it may be beneficial to think of it as having one of these slightly more liberal type signatures:</span>
<a name="line-138"></a><span class='hs-comment'>--</span>
<a name="line-139"></a><span class='hs-comment'>-- @</span>
<a name="line-140"></a><span class='hs-comment'>-- 'review' :: 'MonadReader' a m => 'Iso'' s a -> m s</span>
<a name="line-141"></a><span class='hs-comment'>-- 'review' :: 'MonadReader' a m => 'Prism'' s a -> m s</span>
<a name="line-142"></a><span class='hs-comment'>-- @</span>
<a name="line-143"></a><span class='hs-definition'>review</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>MonadReader</span> <span class='hs-varid'>b</span> <span class='hs-varid'>m</span> <span class='hs-keyglyph'>=></span> <span class='hs-conid'>AReview</span> <span class='hs-varid'>t</span> <span class='hs-varid'>b</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>m</span> <span class='hs-varid'>t</span>
<a name="line-144"></a><span class='hs-definition'>review</span> <span class='hs-varid'>p</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>asks</span> <span class='hs-layout'>(</span><span class='hs-varid'>runIdentity</span> <span class='hs-cpp'>#.</span> <span class='hs-varid'>unTagged</span> <span class='hs-cpp'>#.</span> <span class='hs-varid'>p</span> <span class='hs-varop'>.#</span> <span class='hs-conid'>Tagged</span> <span class='hs-varop'>.#</span> <span class='hs-conid'>Identity</span><span class='hs-layout'>)</span>
<a name="line-145"></a><span class='hs-comment'>{-# INLINE review #-}</span>
<a name="line-146"></a>
<a name="line-147"></a><span class='hs-comment'>-- | An infix alias for 'review'.</span>
<a name="line-148"></a><span class='hs-comment'>--</span>
<a name="line-149"></a><span class='hs-comment'>-- @</span>
<a name="line-150"></a><span class='hs-comment'>-- 'unto' f # x ≡ f x</span>
<a name="line-151"></a><span class='hs-comment'>-- l # x ≡ x '^.' 're' l</span>
<a name="line-152"></a><span class='hs-comment'>-- @</span>
<a name="line-153"></a><span class='hs-comment'>--</span>
<a name="line-154"></a><span class='hs-comment'>-- This is commonly used when using a 'Prism' as a smart constructor.</span>
<a name="line-155"></a><span class='hs-comment'>--</span>
<a name="line-156"></a><span class='hs-comment'>-- >>> _Left # 4</span>
<a name="line-157"></a><span class='hs-comment'>-- Left 4</span>
<a name="line-158"></a><span class='hs-comment'>--</span>
<a name="line-159"></a><span class='hs-comment'>-- But it can be used for any 'Prism'</span>
<a name="line-160"></a><span class='hs-comment'>--</span>
<a name="line-161"></a><span class='hs-comment'>-- >>> base 16 # 123</span>
<a name="line-162"></a><span class='hs-comment'>-- "7b"</span>
<a name="line-163"></a><span class='hs-comment'>--</span>
<a name="line-164"></a><span class='hs-comment'>-- @</span>
<a name="line-165"></a><span class='hs-comment'>-- (#) :: 'Iso'' s a -> a -> s</span>
<a name="line-166"></a><span class='hs-comment'>-- (#) :: 'Prism'' s a -> a -> s</span>
<a name="line-167"></a><span class='hs-comment'>-- (#) :: 'Review' s a -> a -> s</span>
<a name="line-168"></a><span class='hs-comment'>-- (#) :: 'Equality'' s a -> a -> s</span>
<a name="line-169"></a><span class='hs-comment'>-- @</span>
<a name="line-170"></a><span class='hs-layout'>(</span> <span class='hs-cpp'>#</span> <span class='hs-layout'>)</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>AReview</span> <span class='hs-varid'>t</span> <span class='hs-varid'>b</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>b</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>t</span>
<a name="line-171"></a><span class='hs-layout'>(</span> <span class='hs-cpp'>#</span> <span class='hs-layout'>)</span> <span class='hs-varid'>p</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>runIdentity</span> <span class='hs-cpp'>#.</span> <span class='hs-varid'>unTagged</span> <span class='hs-cpp'>#.</span> <span class='hs-varid'>p</span> <span class='hs-varop'>.#</span> <span class='hs-conid'>Tagged</span> <span class='hs-varop'>.#</span> <span class='hs-conid'>Identity</span>
<a name="line-172"></a><span class='hs-comment'>{-# INLINE ( # ) #-}</span>
<a name="line-173"></a>
<a name="line-174"></a><a name="reviews"></a><span class='hs-comment'>-- | This can be used to turn an 'Control.Lens.Iso.Iso' or 'Prism' around and 'view' a value (or the current environment) through it the other way,</span>
<a name="line-175"></a><span class='hs-comment'>-- applying a function.</span>
<a name="line-176"></a><span class='hs-comment'>--</span>
<a name="line-177"></a><span class='hs-comment'>-- @</span>
<a name="line-178"></a><span class='hs-comment'>-- 'reviews' ≡ 'views' '.' 're'</span>
<a name="line-179"></a><span class='hs-comment'>-- 'reviews' ('unto' f) g ≡ g '.' f</span>
<a name="line-180"></a><span class='hs-comment'>-- @</span>
<a name="line-181"></a><span class='hs-comment'>--</span>
<a name="line-182"></a><span class='hs-comment'>-- >>> reviews _Left isRight "mustard"</span>
<a name="line-183"></a><span class='hs-comment'>-- False</span>
<a name="line-184"></a><span class='hs-comment'>--</span>
<a name="line-185"></a><span class='hs-comment'>-- >>> reviews (unto succ) (*2) 3</span>
<a name="line-186"></a><span class='hs-comment'>-- 8</span>
<a name="line-187"></a><span class='hs-comment'>--</span>
<a name="line-188"></a><span class='hs-comment'>-- Usually this function is used in the @(->)@ 'Monad' with a 'Prism' or 'Control.Lens.Iso.Iso', in which case it may be useful to think of</span>
<a name="line-189"></a><span class='hs-comment'>-- it as having one of these more restricted type signatures:</span>
<a name="line-190"></a><span class='hs-comment'>--</span>
<a name="line-191"></a><span class='hs-comment'>-- @</span>
<a name="line-192"></a><span class='hs-comment'>-- 'reviews' :: 'Iso'' s a -> (s -> r) -> a -> r</span>
<a name="line-193"></a><span class='hs-comment'>-- 'reviews' :: 'Prism'' s a -> (s -> r) -> a -> r</span>
<a name="line-194"></a><span class='hs-comment'>-- @</span>
<a name="line-195"></a><span class='hs-comment'>--</span>
<a name="line-196"></a><span class='hs-comment'>-- However, when working with a 'Monad' transformer stack, it is sometimes useful to be able to 'review' the current environment, in which case</span>
<a name="line-197"></a><span class='hs-comment'>-- it may be beneficial to think of it as having one of these slightly more liberal type signatures:</span>
<a name="line-198"></a><span class='hs-comment'>--</span>
<a name="line-199"></a><span class='hs-comment'>-- @</span>
<a name="line-200"></a><span class='hs-comment'>-- 'reviews' :: 'MonadReader' a m => 'Iso'' s a -> (s -> r) -> m r</span>
<a name="line-201"></a><span class='hs-comment'>-- 'reviews' :: 'MonadReader' a m => 'Prism'' s a -> (s -> r) -> m r</span>
<a name="line-202"></a><span class='hs-comment'>-- @</span>
<a name="line-203"></a><span class='hs-definition'>reviews</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>MonadReader</span> <span class='hs-varid'>b</span> <span class='hs-varid'>m</span> <span class='hs-keyglyph'>=></span> <span class='hs-conid'>AReview</span> <span class='hs-varid'>t</span> <span class='hs-varid'>b</span> <span class='hs-keyglyph'>-></span> <span class='hs-layout'>(</span><span class='hs-varid'>t</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>r</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>m</span> <span class='hs-varid'>r</span>
<a name="line-204"></a><span class='hs-definition'>reviews</span> <span class='hs-varid'>p</span> <span class='hs-varid'>tr</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>asks</span> <span class='hs-layout'>(</span><span class='hs-varid'>tr</span> <span class='hs-varop'>.</span> <span class='hs-varid'>runIdentity</span> <span class='hs-cpp'>#.</span> <span class='hs-varid'>unTagged</span> <span class='hs-cpp'>#.</span> <span class='hs-varid'>p</span> <span class='hs-varop'>.#</span> <span class='hs-conid'>Tagged</span> <span class='hs-varop'>.#</span> <span class='hs-conid'>Identity</span><span class='hs-layout'>)</span>
<a name="line-205"></a><span class='hs-comment'>{-# INLINE reviews #-}</span>
<a name="line-206"></a>
<a name="line-207"></a><a name="reuse"></a><span class='hs-comment'>-- | This can be used to turn an 'Control.Lens.Iso.Iso' or 'Prism' around and 'use' a value (or the current environment) through it the other way.</span>
<a name="line-208"></a><span class='hs-comment'>--</span>
<a name="line-209"></a><span class='hs-comment'>-- @</span>
<a name="line-210"></a><span class='hs-comment'>-- 'reuse' ≡ 'use' '.' 're'</span>
<a name="line-211"></a><span class='hs-comment'>-- 'reuse' '.' 'unto' ≡ 'gets'</span>
<a name="line-212"></a><span class='hs-comment'>-- @</span>
<a name="line-213"></a><span class='hs-comment'>--</span>
<a name="line-214"></a><span class='hs-comment'>-- >>> evalState (reuse _Left) 5</span>
<a name="line-215"></a><span class='hs-comment'>-- Left 5</span>
<a name="line-216"></a><span class='hs-comment'>--</span>
<a name="line-217"></a><span class='hs-comment'>-- >>> evalState (reuse (unto succ)) 5</span>
<a name="line-218"></a><span class='hs-comment'>-- 6</span>
<a name="line-219"></a><span class='hs-comment'>--</span>
<a name="line-220"></a><span class='hs-comment'>-- @</span>
<a name="line-221"></a><span class='hs-comment'>-- 'reuse' :: 'MonadState' a m => 'Prism'' s a -> m s</span>
<a name="line-222"></a><span class='hs-comment'>-- 'reuse' :: 'MonadState' a m => 'Iso'' s a -> m s</span>
<a name="line-223"></a><span class='hs-comment'>-- @</span>
<a name="line-224"></a><span class='hs-definition'>reuse</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>MonadState</span> <span class='hs-varid'>b</span> <span class='hs-varid'>m</span> <span class='hs-keyglyph'>=></span> <span class='hs-conid'>AReview</span> <span class='hs-varid'>t</span> <span class='hs-varid'>b</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>m</span> <span class='hs-varid'>t</span>
<a name="line-225"></a><span class='hs-definition'>reuse</span> <span class='hs-varid'>p</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>gets</span> <span class='hs-layout'>(</span><span class='hs-varid'>runIdentity</span> <span class='hs-cpp'>#.</span> <span class='hs-varid'>unTagged</span> <span class='hs-cpp'>#.</span> <span class='hs-varid'>p</span> <span class='hs-varop'>.#</span> <span class='hs-conid'>Tagged</span> <span class='hs-varop'>.#</span> <span class='hs-conid'>Identity</span><span class='hs-layout'>)</span>
<a name="line-226"></a><span class='hs-comment'>{-# INLINE reuse #-}</span>
<a name="line-227"></a>
<a name="line-228"></a><a name="reuses"></a><span class='hs-comment'>-- | This can be used to turn an 'Control.Lens.Iso.Iso' or 'Prism' around and 'use' the current state through it the other way,</span>
<a name="line-229"></a><span class='hs-comment'>-- applying a function.</span>
<a name="line-230"></a><span class='hs-comment'>--</span>
<a name="line-231"></a><span class='hs-comment'>-- @</span>
<a name="line-232"></a><span class='hs-comment'>-- 'reuses' ≡ 'uses' '.' 're'</span>
<a name="line-233"></a><span class='hs-comment'>-- 'reuses' ('unto' f) g ≡ 'gets' (g '.' f)</span>
<a name="line-234"></a><span class='hs-comment'>-- @</span>
<a name="line-235"></a><span class='hs-comment'>--</span>
<a name="line-236"></a><span class='hs-comment'>-- >>> evalState (reuses _Left isLeft) (5 :: Int)</span>
<a name="line-237"></a><span class='hs-comment'>-- True</span>
<a name="line-238"></a><span class='hs-comment'>--</span>
<a name="line-239"></a><span class='hs-comment'>-- @</span>
<a name="line-240"></a><span class='hs-comment'>-- 'reuses' :: 'MonadState' a m => 'Prism'' s a -> (s -> r) -> m r</span>
<a name="line-241"></a><span class='hs-comment'>-- 'reuses' :: 'MonadState' a m => 'Iso'' s a -> (s -> r) -> m r</span>
<a name="line-242"></a><span class='hs-comment'>-- @</span>
<a name="line-243"></a><span class='hs-definition'>reuses</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>MonadState</span> <span class='hs-varid'>b</span> <span class='hs-varid'>m</span> <span class='hs-keyglyph'>=></span> <span class='hs-conid'>AReview</span> <span class='hs-varid'>t</span> <span class='hs-varid'>b</span> <span class='hs-keyglyph'>-></span> <span class='hs-layout'>(</span><span class='hs-varid'>t</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>r</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>m</span> <span class='hs-varid'>r</span>
<a name="line-244"></a><span class='hs-definition'>reuses</span> <span class='hs-varid'>p</span> <span class='hs-varid'>tr</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>gets</span> <span class='hs-layout'>(</span><span class='hs-varid'>tr</span> <span class='hs-varop'>.</span> <span class='hs-varid'>runIdentity</span> <span class='hs-cpp'>#.</span> <span class='hs-varid'>unTagged</span> <span class='hs-cpp'>#.</span> <span class='hs-varid'>p</span> <span class='hs-varop'>.#</span> <span class='hs-conid'>Tagged</span> <span class='hs-varop'>.#</span> <span class='hs-conid'>Identity</span><span class='hs-layout'>)</span>
<a name="line-245"></a><span class='hs-comment'>{-# INLINE reuses #-}</span>
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