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<pre><a name="line-1"></a><span class='hs-comment'>{-# LANGUAGE DeriveDataTypeable #-}</span>
<a name="line-2"></a><span class='hs-comment'>{-# LANGUAGE FlexibleInstances #-}</span>
<a name="line-3"></a><span class='hs-comment'>{-# LANGUAGE MultiParamTypeClasses #-}</span>
<a name="line-4"></a><span class='hs-comment'>{-# LANGUAGE TypeFamilies #-}</span>
<a name="line-5"></a><span class='hs-comment'>-- | This module provides three different datatypes: 'AEither' is the</span>
<a name="line-6"></a><span class='hs-comment'>-- applicative version of Either. It does not provide a monad instance, and</span>
<a name="line-7"></a><span class='hs-comment'>-- 'mappend's together error values. 'MEither' is the monadic version, which</span>
<a name="line-8"></a><span class='hs-comment'>-- only holds onto the first error value. 'MEitherT' is a monad transformer.</span>
<a name="line-9"></a><span class='hs-comment'>--</span>
<a name="line-10"></a><span class='hs-comment'>-- Also, *Either datatypes and utility functions from Data.Either</span>
<a name="line-11"></a><span class='hs-comment'>-- are generalized with 'Neither' type class.</span>
<a name="line-12"></a>
<a name="line-13"></a><span class='hs-keyword'>module</span> <span class='hs-conid'>Data</span><span class='hs-varop'>.</span><span class='hs-conid'>Neither</span>
<a name="line-14"></a> <span class='hs-layout'>(</span> <span class='hs-comment'>-- * Applicative version</span>
<a name="line-15"></a> <span class='hs-conid'>AEither</span> <span class='hs-layout'>(</span><span class='hs-keyglyph'>..</span><span class='hs-layout'>)</span>
<a name="line-16"></a> <span class='hs-layout'>,</span> <span class='hs-varid'>aeither</span>
<a name="line-17"></a> <span class='hs-comment'>-- * Monadic version</span>
<a name="line-18"></a> <span class='hs-layout'>,</span> <span class='hs-conid'>MEither</span> <span class='hs-layout'>(</span><span class='hs-keyglyph'>..</span><span class='hs-layout'>)</span>
<a name="line-19"></a> <span class='hs-layout'>,</span> <span class='hs-varid'>meither</span>
<a name="line-20"></a> <span class='hs-comment'>-- * Monad transformer</span>
<a name="line-21"></a> <span class='hs-layout'>,</span> <span class='hs-conid'>MEitherT</span> <span class='hs-layout'>(</span><span class='hs-keyglyph'>..</span><span class='hs-layout'>)</span>
<a name="line-22"></a> <span class='hs-layout'>,</span> <span class='hs-varid'>mapMEitherT</span>
<a name="line-23"></a> <span class='hs-layout'>,</span> <span class='hs-varid'>throwMEither</span>
<a name="line-24"></a> <span class='hs-comment'>-- * Neither typeclass</span>
<a name="line-25"></a> <span class='hs-layout'>,</span> <span class='hs-conid'>Neither</span> <span class='hs-layout'>(</span><span class='hs-keyglyph'>..</span><span class='hs-layout'>)</span>
<a name="line-26"></a> <span class='hs-comment'>-- * Utility functions</span>
<a name="line-27"></a> <span class='hs-layout'>,</span> <span class='hs-varid'>mapLeft</span>
<a name="line-28"></a> <span class='hs-layout'>,</span> <span class='hs-varid'>mapRight</span>
<a name="line-29"></a> <span class='hs-layout'>,</span> <span class='hs-varid'>mapEither</span>
<a name="line-30"></a> <span class='hs-layout'>,</span> <span class='hs-varid'>lefts</span>
<a name="line-31"></a> <span class='hs-layout'>,</span> <span class='hs-varid'>rights</span>
<a name="line-32"></a> <span class='hs-layout'>,</span> <span class='hs-varid'>partitionEithers</span>
<a name="line-33"></a> <span class='hs-layout'>)</span> <span class='hs-keyword'>where</span>
<a name="line-34"></a>
<a name="line-35"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Prelude</span> <span class='hs-varid'>hiding</span> <span class='hs-layout'>(</span><span class='hs-varid'>either</span><span class='hs-layout'>,</span> <span class='hs-varid'>catch</span><span class='hs-layout'>)</span>
<a name="line-36"></a><span class='hs-keyword'>import</span> <span class='hs-keyword'>qualified</span> <span class='hs-conid'>Data</span><span class='hs-varop'>.</span><span class='hs-conid'>Either</span> <span class='hs-keyword'>as</span> <span class='hs-conid'>E</span>
<a name="line-37"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Control</span><span class='hs-varop'>.</span><span class='hs-conid'>Monad</span>
<a name="line-38"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Control</span><span class='hs-varop'>.</span><span class='hs-conid'>Arrow</span> <span class='hs-layout'>(</span><span class='hs-layout'>(</span><span class='hs-varop'>&&&</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span>
<a name="line-39"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Data</span><span class='hs-varop'>.</span><span class='hs-conid'>Monoid</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'>Applicative</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'>Failure</span>
<a name="line-42"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Data</span><span class='hs-varop'>.</span><span class='hs-conid'>Typeable</span>
<a name="line-43"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Data</span><span class='hs-varop'>.</span><span class='hs-conid'>Data</span>
<a name="line-44"></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'>IO</span><span class='hs-varop'>.</span><span class='hs-conid'>Class</span>
<a name="line-45"></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'>Trans</span><span class='hs-varop'>.</span><span class='hs-conid'>Class</span>
<a name="line-46"></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'>Invert</span>
<a name="line-47"></a>
<a name="line-48"></a><a name="Neither"></a><span class='hs-keyword'>class</span> <span class='hs-conid'>Neither</span> <span class='hs-varid'>e</span> <span class='hs-keyword'>where</span>
<a name="line-49"></a> <span class='hs-varid'>left</span> <span class='hs-keyglyph'>::</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>e</span> <span class='hs-varid'>a</span> <span class='hs-varid'>b</span>
<a name="line-50"></a> <span class='hs-varid'>right</span> <span class='hs-keyglyph'>::</span> <span class='hs-varid'>b</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>e</span> <span class='hs-varid'>a</span> <span class='hs-varid'>b</span>
<a name="line-51"></a> <span class='hs-varid'>either</span> <span class='hs-keyglyph'>::</span> <span class='hs-layout'>(</span><span class='hs-varid'>a</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>c</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'>c</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>e</span> <span class='hs-varid'>a</span> <span class='hs-varid'>b</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>c</span>
<a name="line-52"></a>
<a name="line-53"></a><span class='hs-keyword'>instance</span> <span class='hs-conid'>Neither</span> <span class='hs-conid'>Either</span> <span class='hs-keyword'>where</span>
<a name="line-54"></a> <span class='hs-varid'>left</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>Left</span>
<a name="line-55"></a> <span class='hs-varid'>right</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>Right</span>
<a name="line-56"></a> <span class='hs-varid'>either</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>E</span><span class='hs-varop'>.</span><span class='hs-varid'>either</span>
<a name="line-57"></a>
<a name="line-58"></a><span class='hs-keyword'>instance</span> <span class='hs-conid'>Neither</span> <span class='hs-conid'>MEither</span> <span class='hs-keyword'>where</span>
<a name="line-59"></a> <span class='hs-varid'>left</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>MLeft</span>
<a name="line-60"></a> <span class='hs-varid'>right</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>MRight</span>
<a name="line-61"></a> <span class='hs-varid'>either</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>meither</span>
<a name="line-62"></a>
<a name="line-63"></a><span class='hs-keyword'>instance</span> <span class='hs-conid'>Neither</span> <span class='hs-conid'>AEither</span> <span class='hs-keyword'>where</span>
<a name="line-64"></a> <span class='hs-varid'>left</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>ALeft</span>
<a name="line-65"></a> <span class='hs-varid'>right</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>ARight</span>
<a name="line-66"></a> <span class='hs-varid'>either</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>aeither</span>
<a name="line-67"></a>
<a name="line-68"></a><a name="mapLeft"></a><span class='hs-definition'>mapLeft</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Neither</span> <span class='hs-varid'>e</span> <span class='hs-keyglyph'>=></span> <span class='hs-layout'>(</span><span class='hs-varid'>a</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>c</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>e</span> <span class='hs-varid'>a</span> <span class='hs-varid'>b</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>e</span> <span class='hs-varid'>c</span> <span class='hs-varid'>b</span>
<a name="line-69"></a><span class='hs-definition'>mapLeft</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>flip</span> <span class='hs-varid'>mapEither</span> <span class='hs-varid'>id</span>
<a name="line-70"></a>
<a name="line-71"></a><a name="mapRight"></a><span class='hs-definition'>mapRight</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Neither</span> <span class='hs-varid'>e</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'>c</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>e</span> <span class='hs-varid'>a</span> <span class='hs-varid'>b</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>e</span> <span class='hs-varid'>a</span> <span class='hs-varid'>c</span>
<a name="line-72"></a><span class='hs-definition'>mapRight</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>mapEither</span> <span class='hs-varid'>id</span>
<a name="line-73"></a>
<a name="line-74"></a><a name="mapEither"></a><span class='hs-definition'>mapEither</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Neither</span> <span class='hs-varid'>e</span> <span class='hs-keyglyph'>=></span> <span class='hs-layout'>(</span><span class='hs-varid'>a</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>c</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'>d</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>e</span> <span class='hs-varid'>a</span> <span class='hs-varid'>b</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>e</span> <span class='hs-varid'>c</span> <span class='hs-varid'>d</span>
<a name="line-75"></a><span class='hs-definition'>mapEither</span> <span class='hs-varid'>f</span> <span class='hs-varid'>g</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>either</span> <span class='hs-layout'>(</span><span class='hs-varid'>left</span> <span class='hs-varop'>.</span> <span class='hs-varid'>f</span><span class='hs-layout'>)</span> <span class='hs-layout'>(</span><span class='hs-varid'>right</span> <span class='hs-varop'>.</span> <span class='hs-varid'>g</span><span class='hs-layout'>)</span>
<a name="line-76"></a>
<a name="line-77"></a><a name="lefts"></a><span class='hs-definition'>lefts</span> <span class='hs-keyglyph'>::</span> <span class='hs-layout'>(</span><span class='hs-conid'>Neither</span> <span class='hs-varid'>e</span><span class='hs-layout'>,</span> <span class='hs-conid'>MonadPlus</span> <span class='hs-varid'>m</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=></span> <span class='hs-varid'>m</span> <span class='hs-layout'>(</span><span class='hs-varid'>e</span> <span class='hs-varid'>a</span> <span class='hs-varid'>b</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>m</span> <span class='hs-varid'>a</span>
<a name="line-78"></a><span class='hs-definition'>lefts</span> <span class='hs-keyglyph'>=</span> <span class='hs-layout'>(</span><span class='hs-varop'>=<<</span><span class='hs-layout'>)</span> <span class='hs-varop'>$</span> <span class='hs-varid'>either</span> <span class='hs-varid'>return</span> <span class='hs-layout'>(</span><span class='hs-varid'>const</span> <span class='hs-varid'>mzero</span><span class='hs-layout'>)</span>
<a name="line-79"></a>
<a name="line-80"></a><a name="rights"></a><span class='hs-definition'>rights</span> <span class='hs-keyglyph'>::</span> <span class='hs-layout'>(</span><span class='hs-conid'>Neither</span> <span class='hs-varid'>e</span><span class='hs-layout'>,</span> <span class='hs-conid'>MonadPlus</span> <span class='hs-varid'>m</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=></span> <span class='hs-varid'>m</span> <span class='hs-layout'>(</span><span class='hs-varid'>e</span> <span class='hs-varid'>a</span> <span class='hs-varid'>b</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>m</span> <span class='hs-varid'>b</span>
<a name="line-81"></a><span class='hs-definition'>rights</span> <span class='hs-keyglyph'>=</span> <span class='hs-layout'>(</span><span class='hs-varop'>=<<</span><span class='hs-layout'>)</span> <span class='hs-varop'>$</span> <span class='hs-varid'>either</span> <span class='hs-layout'>(</span><span class='hs-varid'>const</span> <span class='hs-varid'>mzero</span><span class='hs-layout'>)</span> <span class='hs-varid'>return</span>
<a name="line-82"></a>
<a name="line-83"></a><a name="partitionEithers"></a><span class='hs-definition'>partitionEithers</span> <span class='hs-keyglyph'>::</span> <span class='hs-layout'>(</span><span class='hs-conid'>Neither</span> <span class='hs-varid'>e</span><span class='hs-layout'>,</span> <span class='hs-conid'>MonadPlus</span> <span class='hs-varid'>m</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=></span> <span class='hs-varid'>m</span> <span class='hs-layout'>(</span><span class='hs-varid'>e</span> <span class='hs-varid'>a</span> <span class='hs-varid'>b</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>-></span> <span class='hs-layout'>(</span><span class='hs-varid'>m</span> <span class='hs-varid'>a</span><span class='hs-layout'>,</span> <span class='hs-varid'>m</span> <span class='hs-varid'>b</span><span class='hs-layout'>)</span>
<a name="line-84"></a><span class='hs-definition'>partitionEithers</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>lefts</span> <span class='hs-varop'>&&&</span> <span class='hs-varid'>rights</span>
<a name="line-85"></a>
<a name="line-86"></a><a name="MEither"></a><span class='hs-keyword'>data</span> <span class='hs-conid'>MEither</span> <span class='hs-varid'>a</span> <span class='hs-varid'>b</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>MLeft</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>|</span> <span class='hs-conid'>MRight</span> <span class='hs-varid'>b</span>
<a name="line-87"></a> <span class='hs-keyword'>deriving</span> <span class='hs-layout'>(</span><span class='hs-conid'>Typeable</span><span class='hs-layout'>,</span> <span class='hs-conid'>Eq</span><span class='hs-layout'>,</span> <span class='hs-conid'>Data</span><span class='hs-layout'>,</span> <span class='hs-conid'>Ord</span><span class='hs-layout'>,</span> <span class='hs-conid'>Read</span><span class='hs-layout'>,</span> <span class='hs-conid'>Show</span><span class='hs-layout'>)</span>
<a name="line-88"></a><span class='hs-keyword'>instance</span> <span class='hs-conid'>Monad</span> <span class='hs-layout'>(</span><span class='hs-conid'>MEither</span> <span class='hs-varid'>a</span><span class='hs-layout'>)</span> <span class='hs-keyword'>where</span>
<a name="line-89"></a> <span class='hs-varid'>return</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>MRight</span>
<a name="line-90"></a> <span class='hs-layout'>(</span><span class='hs-conid'>MLeft</span> <span class='hs-varid'>a</span><span class='hs-layout'>)</span> <span class='hs-varop'>>>=</span> <span class='hs-keyword'>_</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>MLeft</span> <span class='hs-varid'>a</span>
<a name="line-91"></a> <span class='hs-layout'>(</span><span class='hs-conid'>MRight</span> <span class='hs-varid'>b</span><span class='hs-layout'>)</span> <span class='hs-varop'>>>=</span> <span class='hs-varid'>f</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>f</span> <span class='hs-varid'>b</span>
<a name="line-92"></a><span class='hs-keyword'>instance</span> <span class='hs-conid'>Functor</span> <span class='hs-layout'>(</span><span class='hs-conid'>MEither</span> <span class='hs-varid'>a</span><span class='hs-layout'>)</span> <span class='hs-keyword'>where</span>
<a name="line-93"></a> <span class='hs-varid'>fmap</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>liftM</span>
<a name="line-94"></a><span class='hs-keyword'>instance</span> <span class='hs-conid'>Applicative</span> <span class='hs-layout'>(</span><span class='hs-conid'>MEither</span> <span class='hs-varid'>a</span><span class='hs-layout'>)</span> <span class='hs-keyword'>where</span>
<a name="line-95"></a> <span class='hs-varid'>pure</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>return</span>
<a name="line-96"></a> <span class='hs-layout'>(</span><span class='hs-varop'><*></span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>ap</span>
<a name="line-97"></a><span class='hs-keyword'>instance</span> <span class='hs-conid'>Failure</span> <span class='hs-varid'>e</span> <span class='hs-layout'>(</span><span class='hs-conid'>MEither</span> <span class='hs-varid'>e</span><span class='hs-layout'>)</span> <span class='hs-keyword'>where</span>
<a name="line-98"></a> <span class='hs-varid'>failure</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>MLeft</span>
<a name="line-99"></a><a name="meither"></a><span class='hs-definition'>meither</span> <span class='hs-keyglyph'>::</span> <span class='hs-layout'>(</span><span class='hs-varid'>a</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>c</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'>c</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>MEither</span> <span class='hs-varid'>a</span> <span class='hs-varid'>b</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>c</span>
<a name="line-100"></a><span class='hs-definition'>meither</span> <span class='hs-varid'>f</span> <span class='hs-keyword'>_</span> <span class='hs-layout'>(</span><span class='hs-conid'>MLeft</span> <span class='hs-varid'>a</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>f</span> <span class='hs-varid'>a</span>
<a name="line-101"></a><span class='hs-definition'>meither</span> <span class='hs-keyword'>_</span> <span class='hs-varid'>f</span> <span class='hs-layout'>(</span><span class='hs-conid'>MRight</span> <span class='hs-varid'>b</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>f</span> <span class='hs-varid'>b</span>
<a name="line-102"></a>
<a name="line-103"></a><a name="AEither"></a><span class='hs-keyword'>data</span> <span class='hs-conid'>AEither</span> <span class='hs-varid'>a</span> <span class='hs-varid'>b</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>ALeft</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>|</span> <span class='hs-conid'>ARight</span> <span class='hs-varid'>b</span>
<a name="line-104"></a> <span class='hs-keyword'>deriving</span> <span class='hs-layout'>(</span><span class='hs-conid'>Typeable</span><span class='hs-layout'>,</span> <span class='hs-conid'>Eq</span><span class='hs-layout'>,</span> <span class='hs-conid'>Data</span><span class='hs-layout'>,</span> <span class='hs-conid'>Ord</span><span class='hs-layout'>,</span> <span class='hs-conid'>Read</span><span class='hs-layout'>,</span> <span class='hs-conid'>Show</span><span class='hs-layout'>)</span>
<a name="line-105"></a><span class='hs-keyword'>instance</span> <span class='hs-conid'>Functor</span> <span class='hs-layout'>(</span><span class='hs-conid'>AEither</span> <span class='hs-varid'>a</span><span class='hs-layout'>)</span> <span class='hs-keyword'>where</span>
<a name="line-106"></a> <span class='hs-varid'>fmap</span> <span class='hs-keyword'>_</span> <span class='hs-layout'>(</span><span class='hs-conid'>ALeft</span> <span class='hs-varid'>a</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>ALeft</span> <span class='hs-varid'>a</span>
<a name="line-107"></a> <span class='hs-varid'>fmap</span> <span class='hs-varid'>f</span> <span class='hs-layout'>(</span><span class='hs-conid'>ARight</span> <span class='hs-varid'>b</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>ARight</span> <span class='hs-varop'>$</span> <span class='hs-varid'>f</span> <span class='hs-varid'>b</span>
<a name="line-108"></a><span class='hs-keyword'>instance</span> <span class='hs-conid'>Monoid</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>=></span> <span class='hs-conid'>Applicative</span> <span class='hs-layout'>(</span><span class='hs-conid'>AEither</span> <span class='hs-varid'>a</span><span class='hs-layout'>)</span> <span class='hs-keyword'>where</span>
<a name="line-109"></a> <span class='hs-varid'>pure</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>ARight</span>
<a name="line-110"></a> <span class='hs-conid'>ALeft</span> <span class='hs-varid'>x</span> <span class='hs-varop'><*></span> <span class='hs-conid'>ALeft</span> <span class='hs-varid'>y</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>ALeft</span> <span class='hs-varop'>$</span> <span class='hs-varid'>x</span> <span class='hs-varop'>`mappend`</span> <span class='hs-varid'>y</span>
<a name="line-111"></a> <span class='hs-conid'>ALeft</span> <span class='hs-varid'>x</span> <span class='hs-varop'><*></span> <span class='hs-keyword'>_</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>ALeft</span> <span class='hs-varid'>x</span>
<a name="line-112"></a> <span class='hs-keyword'>_</span> <span class='hs-varop'><*></span> <span class='hs-conid'>ALeft</span> <span class='hs-varid'>y</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>ALeft</span> <span class='hs-varid'>y</span>
<a name="line-113"></a> <span class='hs-conid'>ARight</span> <span class='hs-varid'>x</span> <span class='hs-varop'><*></span> <span class='hs-conid'>ARight</span> <span class='hs-varid'>y</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>ARight</span> <span class='hs-varop'>$</span> <span class='hs-varid'>x</span> <span class='hs-varid'>y</span>
<a name="line-114"></a><a name="aeither"></a><span class='hs-definition'>aeither</span> <span class='hs-keyglyph'>::</span> <span class='hs-layout'>(</span><span class='hs-varid'>a</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>c</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'>c</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>AEither</span> <span class='hs-varid'>a</span> <span class='hs-varid'>b</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>c</span>
<a name="line-115"></a><span class='hs-definition'>aeither</span> <span class='hs-varid'>f</span> <span class='hs-keyword'>_</span> <span class='hs-layout'>(</span><span class='hs-conid'>ALeft</span> <span class='hs-varid'>a</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>f</span> <span class='hs-varid'>a</span>
<a name="line-116"></a><span class='hs-definition'>aeither</span> <span class='hs-keyword'>_</span> <span class='hs-varid'>f</span> <span class='hs-layout'>(</span><span class='hs-conid'>ARight</span> <span class='hs-varid'>b</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>f</span> <span class='hs-varid'>b</span>
<a name="line-117"></a>
<a name="line-118"></a><a name="MEitherT"></a><span class='hs-keyword'>newtype</span> <span class='hs-conid'>MEitherT</span> <span class='hs-varid'>e</span> <span class='hs-varid'>m</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>MEitherT</span>
<a name="line-119"></a> <span class='hs-layout'>{</span> <span class='hs-varid'>runMEitherT</span> <span class='hs-keyglyph'>::</span> <span class='hs-varid'>m</span> <span class='hs-layout'>(</span><span class='hs-conid'>MEither</span> <span class='hs-varid'>e</span> <span class='hs-varid'>a</span><span class='hs-layout'>)</span>
<a name="line-120"></a> <span class='hs-layout'>}</span>
<a name="line-121"></a><a name="mapMEitherT"></a><span class='hs-definition'>mapMEitherT</span> <span class='hs-keyglyph'>::</span> <span class='hs-layout'>(</span><span class='hs-varid'>m</span> <span class='hs-layout'>(</span><span class='hs-conid'>MEither</span> <span class='hs-varid'>e</span> <span class='hs-varid'>a</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>n</span> <span class='hs-layout'>(</span><span class='hs-conid'>MEither</span> <span class='hs-varid'>e'</span> <span class='hs-varid'>b</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span>
<a name="line-122"></a> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>MEitherT</span> <span class='hs-varid'>e</span> <span class='hs-varid'>m</span> <span class='hs-varid'>a</span>
<a name="line-123"></a> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>MEitherT</span> <span class='hs-varid'>e'</span> <span class='hs-varid'>n</span> <span class='hs-varid'>b</span>
<a name="line-124"></a><span class='hs-definition'>mapMEitherT</span> <span class='hs-varid'>f</span> <span class='hs-varid'>m</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>MEitherT</span> <span class='hs-varop'>$</span> <span class='hs-varid'>f</span> <span class='hs-layout'>(</span><span class='hs-varid'>runMEitherT</span> <span class='hs-varid'>m</span><span class='hs-layout'>)</span>
<a name="line-125"></a>
<a name="line-126"></a><a name="throwMEither"></a><span class='hs-definition'>throwMEither</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Monad</span> <span class='hs-varid'>m</span> <span class='hs-keyglyph'>=></span> <span class='hs-varid'>e</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>MEitherT</span> <span class='hs-varid'>e</span> <span class='hs-varid'>m</span> <span class='hs-varid'>a</span>
<a name="line-127"></a><span class='hs-definition'>throwMEither</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>MEitherT</span> <span class='hs-varop'>.</span> <span class='hs-varid'>return</span> <span class='hs-varop'>.</span> <span class='hs-conid'>MLeft</span>
<a name="line-128"></a>
<a name="line-129"></a><span class='hs-keyword'>instance</span> <span class='hs-conid'>Functor</span> <span class='hs-varid'>m</span> <span class='hs-keyglyph'>=></span> <span class='hs-conid'>Functor</span> <span class='hs-layout'>(</span><span class='hs-conid'>MEitherT</span> <span class='hs-varid'>e</span> <span class='hs-varid'>m</span><span class='hs-layout'>)</span> <span class='hs-keyword'>where</span>
<a name="line-130"></a> <span class='hs-varid'>fmap</span> <span class='hs-varid'>f</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>MEitherT</span> <span class='hs-varop'>.</span> <span class='hs-varid'>fmap</span> <span class='hs-layout'>(</span><span class='hs-varid'>fmap</span> <span class='hs-varid'>f</span><span class='hs-layout'>)</span> <span class='hs-varop'>.</span> <span class='hs-varid'>runMEitherT</span>
<a name="line-131"></a><span class='hs-keyword'>instance</span> <span class='hs-layout'>(</span><span class='hs-conid'>Functor</span> <span class='hs-varid'>m</span><span class='hs-layout'>,</span> <span class='hs-conid'>Monad</span> <span class='hs-varid'>m</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=></span> <span class='hs-conid'>Applicative</span> <span class='hs-layout'>(</span><span class='hs-conid'>MEitherT</span> <span class='hs-varid'>e</span> <span class='hs-varid'>m</span><span class='hs-layout'>)</span> <span class='hs-keyword'>where</span>
<a name="line-132"></a> <span class='hs-varid'>pure</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>return</span>
<a name="line-133"></a> <span class='hs-layout'>(</span><span class='hs-varop'><*></span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>ap</span>
<a name="line-134"></a><span class='hs-keyword'>instance</span> <span class='hs-conid'>Monad</span> <span class='hs-varid'>m</span> <span class='hs-keyglyph'>=></span> <span class='hs-conid'>Monad</span> <span class='hs-layout'>(</span><span class='hs-conid'>MEitherT</span> <span class='hs-varid'>e</span> <span class='hs-varid'>m</span><span class='hs-layout'>)</span> <span class='hs-keyword'>where</span>
<a name="line-135"></a> <span class='hs-varid'>return</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>MEitherT</span> <span class='hs-varop'>.</span> <span class='hs-varid'>return</span> <span class='hs-varop'>.</span> <span class='hs-varid'>return</span>
<a name="line-136"></a> <span class='hs-layout'>(</span><span class='hs-conid'>MEitherT</span> <span class='hs-varid'>x</span><span class='hs-layout'>)</span> <span class='hs-varop'>>>=</span> <span class='hs-varid'>f</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>MEitherT</span> <span class='hs-varop'>$</span>
<a name="line-137"></a> <span class='hs-varid'>x</span> <span class='hs-varop'>>>=</span> <span class='hs-varid'>meither</span> <span class='hs-layout'>(</span><span class='hs-varid'>return</span> <span class='hs-varop'>.</span> <span class='hs-conid'>MLeft</span><span class='hs-layout'>)</span> <span class='hs-layout'>(</span><span class='hs-varid'>runMEitherT</span> <span class='hs-varop'>.</span> <span class='hs-varid'>f</span><span class='hs-layout'>)</span>
<a name="line-138"></a><span class='hs-keyword'>instance</span> <span class='hs-conid'>Monad</span> <span class='hs-varid'>m</span> <span class='hs-keyglyph'>=></span> <span class='hs-conid'>Failure</span> <span class='hs-varid'>e</span> <span class='hs-layout'>(</span><span class='hs-conid'>MEitherT</span> <span class='hs-varid'>e</span> <span class='hs-varid'>m</span><span class='hs-layout'>)</span> <span class='hs-keyword'>where</span>
<a name="line-139"></a> <span class='hs-varid'>failure</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>MEitherT</span> <span class='hs-varop'>.</span> <span class='hs-varid'>return</span> <span class='hs-varop'>.</span> <span class='hs-conid'>MLeft</span>
<a name="line-140"></a><span class='hs-keyword'>instance</span> <span class='hs-conid'>MonadTrans</span> <span class='hs-layout'>(</span><span class='hs-conid'>MEitherT</span> <span class='hs-varid'>e</span><span class='hs-layout'>)</span> <span class='hs-keyword'>where</span>
<a name="line-141"></a> <span class='hs-varid'>lift</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>MEitherT</span> <span class='hs-varop'>.</span> <span class='hs-varid'>liftM</span> <span class='hs-conid'>MRight</span>
<a name="line-142"></a><span class='hs-keyword'>instance</span> <span class='hs-conid'>MonadIO</span> <span class='hs-varid'>m</span> <span class='hs-keyglyph'>=></span> <span class='hs-conid'>MonadIO</span> <span class='hs-layout'>(</span><span class='hs-conid'>MEitherT</span> <span class='hs-varid'>e</span> <span class='hs-varid'>m</span><span class='hs-layout'>)</span> <span class='hs-keyword'>where</span>
<a name="line-143"></a> <span class='hs-varid'>liftIO</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>lift</span> <span class='hs-varop'>.</span> <span class='hs-varid'>liftIO</span>
<a name="line-144"></a>
<a name="line-145"></a><span class='hs-keyword'>instance</span> <span class='hs-conid'>MonadInvertIO</span> <span class='hs-varid'>m</span> <span class='hs-keyglyph'>=></span> <span class='hs-conid'>MonadInvertIO</span> <span class='hs-layout'>(</span><span class='hs-conid'>MEitherT</span> <span class='hs-varid'>e</span> <span class='hs-varid'>m</span><span class='hs-layout'>)</span> <span class='hs-keyword'>where</span>
<a name="line-146"></a> <span class='hs-keyword'>newtype</span> <span class='hs-conid'>InvertedIO</span> <span class='hs-layout'>(</span><span class='hs-conid'>MEitherT</span> <span class='hs-varid'>e</span> <span class='hs-varid'>m</span><span class='hs-layout'>)</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>=</span>
<a name="line-147"></a> <span class='hs-conid'>InvErrorIO</span> <span class='hs-layout'>{</span> <span class='hs-varid'>runInvErrorIO</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>InvertedIO</span> <span class='hs-varid'>m</span> <span class='hs-layout'>(</span><span class='hs-conid'>MEither</span> <span class='hs-varid'>e</span> <span class='hs-varid'>a</span><span class='hs-layout'>)</span> <span class='hs-layout'>}</span>
<a name="line-148"></a> <span class='hs-keyword'>type</span> <span class='hs-conid'>InvertedArg</span> <span class='hs-layout'>(</span><span class='hs-conid'>MEitherT</span> <span class='hs-varid'>e</span> <span class='hs-varid'>m</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>InvertedArg</span> <span class='hs-varid'>m</span>
<a name="line-149"></a> <span class='hs-varid'>invertIO</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>liftM</span> <span class='hs-layout'>(</span><span class='hs-varid'>fmap</span> <span class='hs-conid'>InvErrorIO</span><span class='hs-layout'>)</span> <span class='hs-varop'>.</span> <span class='hs-varid'>invertIO</span> <span class='hs-varop'>.</span> <span class='hs-varid'>runMEitherT</span>
<a name="line-150"></a> <span class='hs-varid'>revertIO</span> <span class='hs-varid'>f</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>MEitherT</span> <span class='hs-varop'>$</span> <span class='hs-varid'>revertIO</span> <span class='hs-varop'>$</span> <span class='hs-varid'>liftM</span> <span class='hs-varid'>runInvErrorIO</span> <span class='hs-varop'>.</span> <span class='hs-varid'>f</span>
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