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<title>src/Servant/Server/Internal/RoutingApplication.hs</title>
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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 DeriveFunctor #-}</span>
<a name="line-3"></a><span class='hs-comment'>{-# LANGUAGE OverloadedStrings #-}</span>
<a name="line-4"></a><span class='hs-comment'>{-# LANGUAGE TypeOperators #-}</span>
<a name="line-5"></a><span class='hs-comment'>{-# LANGUAGE GADTs #-}</span>
<a name="line-6"></a><span class='hs-comment'>{-# LANGUAGE KindSignatures #-}</span>
<a name="line-7"></a><span class='hs-comment'>{-# LANGUAGE RecordWildCards #-}</span>
<a name="line-8"></a><span class='hs-comment'>{-# LANGUAGE StandaloneDeriving #-}</span>
<a name="line-9"></a><span class='hs-keyword'>module</span> <span class='hs-conid'>Servant</span><span class='hs-varop'>.</span><span class='hs-conid'>Server</span><span class='hs-varop'>.</span><span class='hs-conid'>Internal</span><span class='hs-varop'>.</span><span class='hs-conid'>RoutingApplication</span> <span class='hs-keyword'>where</span>
<a name="line-10"></a>
<a name="line-11"></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-layout'>(</span><span class='hs-varid'>ap</span><span class='hs-layout'>,</span> <span class='hs-varid'>liftM</span><span class='hs-layout'>)</span>
<a name="line-12"></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-layout'>(</span><span class='hs-conid'>MonadIO</span><span class='hs-layout'>(</span><span class='hs-keyglyph'>..</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span>
<a name="line-13"></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'>Except</span> <span class='hs-layout'>(</span><span class='hs-varid'>runExceptT</span><span class='hs-layout'>)</span>
<a name="line-14"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Network</span><span class='hs-varop'>.</span><span class='hs-conid'>Wai</span> <span class='hs-layout'>(</span><span class='hs-conid'>Application</span><span class='hs-layout'>,</span> <span class='hs-conid'>Request</span><span class='hs-layout'>,</span>
<a name="line-15"></a> <span class='hs-conid'>Response</span><span class='hs-layout'>,</span> <span class='hs-conid'>ResponseReceived</span><span class='hs-layout'>)</span>
<a name="line-16"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Prelude</span> <span class='hs-conid'>()</span>
<a name="line-17"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Prelude</span><span class='hs-varop'>.</span><span class='hs-conid'>Compat</span>
<a name="line-18"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Servant</span><span class='hs-varop'>.</span><span class='hs-conid'>Server</span><span class='hs-varop'>.</span><span class='hs-conid'>Internal</span><span class='hs-varop'>.</span><span class='hs-conid'>ServantErr</span>
<a name="line-19"></a>
<a name="line-20"></a><a name="RoutingApplication"></a><span class='hs-keyword'>type</span> <span class='hs-conid'>RoutingApplication</span> <span class='hs-keyglyph'>=</span>
<a name="line-21"></a> <span class='hs-conid'>Request</span> <span class='hs-comment'>-- ^ the request, the field 'pathInfo' may be modified by url routing</span>
<a name="line-22"></a> <span class='hs-keyglyph'>-></span> <span class='hs-layout'>(</span><span class='hs-conid'>RouteResult</span> <span class='hs-conid'>Response</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>IO</span> <span class='hs-conid'>ResponseReceived</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>IO</span> <span class='hs-conid'>ResponseReceived</span>
<a name="line-23"></a>
<a name="line-24"></a><a name="RouteResult"></a><span class='hs-comment'>-- | The result of matching against a path in the route tree.</span>
<a name="line-25"></a><a name="RouteResult"></a><span class='hs-keyword'>data</span> <span class='hs-conid'>RouteResult</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>=</span>
<a name="line-26"></a> <span class='hs-conid'>Fail</span> <span class='hs-conid'>ServantErr</span> <span class='hs-comment'>-- ^ Keep trying other paths. The @ServantErr@</span>
<a name="line-27"></a> <span class='hs-comment'>-- should only be 404, 405 or 406.</span>
<a name="line-28"></a> <span class='hs-keyglyph'>|</span> <span class='hs-conid'>FailFatal</span> <span class='hs-varop'>!</span><span class='hs-conid'>ServantErr</span> <span class='hs-comment'>-- ^ Don't try other paths.</span>
<a name="line-29"></a> <span class='hs-keyglyph'>|</span> <span class='hs-conid'>Route</span> <span class='hs-varop'>!</span><span class='hs-varid'>a</span>
<a name="line-30"></a> <span class='hs-keyword'>deriving</span> <span class='hs-layout'>(</span><span class='hs-conid'>Eq</span><span class='hs-layout'>,</span> <span class='hs-conid'>Show</span><span class='hs-layout'>,</span> <span class='hs-conid'>Read</span><span class='hs-layout'>,</span> <span class='hs-conid'>Functor</span><span class='hs-layout'>)</span>
<a name="line-31"></a>
<a name="line-32"></a><a name="toApplication"></a><span class='hs-definition'>toApplication</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>RoutingApplication</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Application</span>
<a name="line-33"></a><span class='hs-definition'>toApplication</span> <span class='hs-varid'>ra</span> <span class='hs-varid'>request</span> <span class='hs-varid'>respond</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>ra</span> <span class='hs-varid'>request</span> <span class='hs-varid'>routingRespond</span>
<a name="line-34"></a> <span class='hs-keyword'>where</span>
<a name="line-35"></a> <span class='hs-varid'>routingRespond</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>RouteResult</span> <span class='hs-conid'>Response</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>IO</span> <span class='hs-conid'>ResponseReceived</span>
<a name="line-36"></a> <span class='hs-varid'>routingRespond</span> <span class='hs-layout'>(</span><span class='hs-conid'>Fail</span> <span class='hs-varid'>err</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>respond</span> <span class='hs-varop'>$</span> <span class='hs-varid'>responseServantErr</span> <span class='hs-varid'>err</span>
<a name="line-37"></a> <span class='hs-varid'>routingRespond</span> <span class='hs-layout'>(</span><span class='hs-conid'>FailFatal</span> <span class='hs-varid'>err</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>respond</span> <span class='hs-varop'>$</span> <span class='hs-varid'>responseServantErr</span> <span class='hs-varid'>err</span>
<a name="line-38"></a> <span class='hs-varid'>routingRespond</span> <span class='hs-layout'>(</span><span class='hs-conid'>Route</span> <span class='hs-varid'>v</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>respond</span> <span class='hs-varid'>v</span>
<a name="line-39"></a>
<a name="line-40"></a><a name="Delayed"></a><span class='hs-comment'>-- | A 'Delayed' is a representation of a handler with scheduled</span>
<a name="line-41"></a><a name="Delayed"></a><span class='hs-comment'>-- delayed checks that can trigger errors.</span>
<a name="line-42"></a><a name="Delayed"></a><span class='hs-comment'>--</span>
<a name="line-43"></a><a name="Delayed"></a><span class='hs-comment'>-- Why would we want to delay checks?</span>
<a name="line-44"></a><a name="Delayed"></a><span class='hs-comment'>--</span>
<a name="line-45"></a><a name="Delayed"></a><span class='hs-comment'>-- There are two reasons:</span>
<a name="line-46"></a><a name="Delayed"></a><span class='hs-comment'>--</span>
<a name="line-47"></a><a name="Delayed"></a><span class='hs-comment'>-- 1. In a straight-forward implementation, the order in which we</span>
<a name="line-48"></a><a name="Delayed"></a><span class='hs-comment'>-- perform checks will determine the error we generate. This is</span>
<a name="line-49"></a><a name="Delayed"></a><span class='hs-comment'>-- because once an error occurs, we would abort and not perform</span>
<a name="line-50"></a><a name="Delayed"></a><span class='hs-comment'>-- any subsequent checks, but rather return the current error.</span>
<a name="line-51"></a><a name="Delayed"></a><span class='hs-comment'>--</span>
<a name="line-52"></a><a name="Delayed"></a><span class='hs-comment'>-- This is not a necessity: we could continue doing other checks,</span>
<a name="line-53"></a><a name="Delayed"></a><span class='hs-comment'>-- and choose the preferred error. However, that would in general</span>
<a name="line-54"></a><a name="Delayed"></a><span class='hs-comment'>-- mean more checking, which leads us to the other reason.</span>
<a name="line-55"></a><a name="Delayed"></a><span class='hs-comment'>--</span>
<a name="line-56"></a><a name="Delayed"></a><span class='hs-comment'>-- 2. We really want to avoid doing certain checks too early. For</span>
<a name="line-57"></a><a name="Delayed"></a><span class='hs-comment'>-- example, captures involve parsing, and are much more costly</span>
<a name="line-58"></a><a name="Delayed"></a><span class='hs-comment'>-- than static route matches. In particular, if several paths</span>
<a name="line-59"></a><a name="Delayed"></a><span class='hs-comment'>-- contain the "same" capture, we'd like as much as possible to</span>
<a name="line-60"></a><a name="Delayed"></a><span class='hs-comment'>-- avoid trying the same parse many times. Also tricky is the</span>
<a name="line-61"></a><a name="Delayed"></a><span class='hs-comment'>-- request body. Again, this involves parsing, but also, WAI makes</span>
<a name="line-62"></a><a name="Delayed"></a><span class='hs-comment'>-- obtaining the request body a side-effecting operation. We</span>
<a name="line-63"></a><a name="Delayed"></a><span class='hs-comment'>-- could/can work around this by manually caching the request body,</span>
<a name="line-64"></a><a name="Delayed"></a><span class='hs-comment'>-- but we'd rather keep the number of times we actually try to</span>
<a name="line-65"></a><a name="Delayed"></a><span class='hs-comment'>-- decode the request body to an absolute minimum.</span>
<a name="line-66"></a><a name="Delayed"></a><span class='hs-comment'>--</span>
<a name="line-67"></a><a name="Delayed"></a><span class='hs-comment'>-- We prefer to have the following relative priorities of error</span>
<a name="line-68"></a><a name="Delayed"></a><span class='hs-comment'>-- codes:</span>
<a name="line-69"></a><a name="Delayed"></a><span class='hs-comment'>--</span>
<a name="line-70"></a><a name="Delayed"></a><span class='hs-comment'>-- @</span>
<a name="line-71"></a><a name="Delayed"></a><span class='hs-comment'>-- 404</span>
<a name="line-72"></a><a name="Delayed"></a><span class='hs-comment'>-- 405 (bad method)</span>
<a name="line-73"></a><a name="Delayed"></a><span class='hs-comment'>-- 401 (unauthorized)</span>
<a name="line-74"></a><a name="Delayed"></a><span class='hs-comment'>-- 415 (unsupported media type)</span>
<a name="line-75"></a><a name="Delayed"></a><span class='hs-comment'>-- 400 (bad request)</span>
<a name="line-76"></a><a name="Delayed"></a><span class='hs-comment'>-- 406 (not acceptable)</span>
<a name="line-77"></a><a name="Delayed"></a><span class='hs-comment'>-- @</span>
<a name="line-78"></a><a name="Delayed"></a><span class='hs-comment'>--</span>
<a name="line-79"></a><a name="Delayed"></a><span class='hs-comment'>-- Therefore, while routing, we delay most checks so that they</span>
<a name="line-80"></a><a name="Delayed"></a><span class='hs-comment'>-- will ultimately occur in the right order.</span>
<a name="line-81"></a><a name="Delayed"></a><span class='hs-comment'>--</span>
<a name="line-82"></a><a name="Delayed"></a><span class='hs-comment'>-- A 'Delayed' contains three delayed blocks of tests, and</span>
<a name="line-83"></a><a name="Delayed"></a><span class='hs-comment'>-- the actual handler:</span>
<a name="line-84"></a><a name="Delayed"></a><span class='hs-comment'>--</span>
<a name="line-85"></a><a name="Delayed"></a><span class='hs-comment'>-- 1. Delayed captures. These can actually cause 404, and</span>
<a name="line-86"></a><a name="Delayed"></a><span class='hs-comment'>-- while they're costly, they should be done first among the</span>
<a name="line-87"></a><a name="Delayed"></a><span class='hs-comment'>-- delayed checks (at least as long as we do not decouple the</span>
<a name="line-88"></a><a name="Delayed"></a><span class='hs-comment'>-- check order from the error reporting, see above). Delayed</span>
<a name="line-89"></a><a name="Delayed"></a><span class='hs-comment'>-- captures can provide inputs to the actual handler.</span>
<a name="line-90"></a><a name="Delayed"></a><span class='hs-comment'>--</span>
<a name="line-91"></a><a name="Delayed"></a><span class='hs-comment'>-- 2. Method check(s). This can cause a 405. On success,</span>
<a name="line-92"></a><a name="Delayed"></a><span class='hs-comment'>-- it does not provide an input for the handler. Method checks</span>
<a name="line-93"></a><a name="Delayed"></a><span class='hs-comment'>-- are comparatively cheap.</span>
<a name="line-94"></a><a name="Delayed"></a><span class='hs-comment'>--</span>
<a name="line-95"></a><a name="Delayed"></a><span class='hs-comment'>-- 3. Body and accept header checks. The request body check can</span>
<a name="line-96"></a><a name="Delayed"></a><span class='hs-comment'>-- cause both 400 and 415. This provides an input to the handler.</span>
<a name="line-97"></a><a name="Delayed"></a><span class='hs-comment'>-- The accept header check can be performed as the final</span>
<a name="line-98"></a><a name="Delayed"></a><span class='hs-comment'>-- computation in this block. It can cause a 406.</span>
<a name="line-99"></a><a name="Delayed"></a><span class='hs-comment'>--</span>
<a name="line-100"></a><a name="Delayed"></a><span class='hs-keyword'>data</span> <span class='hs-conid'>Delayed</span> <span class='hs-varid'>env</span> <span class='hs-varid'>c</span> <span class='hs-keyword'>where</span>
<a name="line-101"></a> <span class='hs-conid'>Delayed</span> <span class='hs-keyglyph'>::</span> <span class='hs-layout'>{</span> <span class='hs-varid'>capturesD</span> <span class='hs-keyglyph'>::</span> <span class='hs-varid'>env</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>DelayedIO</span> <span class='hs-varid'>captures</span>
<a name="line-102"></a> <span class='hs-layout'>,</span> <span class='hs-varid'>methodD</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>DelayedIO</span> <span class='hs-conid'>()</span>
<a name="line-103"></a> <span class='hs-layout'>,</span> <span class='hs-varid'>authD</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>DelayedIO</span> <span class='hs-varid'>auth</span>
<a name="line-104"></a> <span class='hs-layout'>,</span> <span class='hs-varid'>bodyD</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>DelayedIO</span> <span class='hs-varid'>body</span>
<a name="line-105"></a> <span class='hs-layout'>,</span> <span class='hs-varid'>serverD</span> <span class='hs-keyglyph'>::</span> <span class='hs-varid'>captures</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>auth</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>body</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Request</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>RouteResult</span> <span class='hs-varid'>c</span>
<a name="line-106"></a> <span class='hs-layout'>}</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Delayed</span> <span class='hs-varid'>env</span> <span class='hs-varid'>c</span>
<a name="line-107"></a>
<a name="line-108"></a><a name="instance%20Functor%20(Delayed%20env)"></a><span class='hs-keyword'>instance</span> <span class='hs-conid'>Functor</span> <span class='hs-layout'>(</span><span class='hs-conid'>Delayed</span> <span class='hs-varid'>env</span><span class='hs-layout'>)</span> <span class='hs-keyword'>where</span>
<a name="line-109"></a> <span class='hs-varid'>fmap</span> <span class='hs-varid'>f</span> <span class='hs-conid'>Delayed</span><span class='hs-layout'>{</span><span class='hs-keyglyph'>..</span><span class='hs-layout'>}</span> <span class='hs-keyglyph'>=</span>
<a name="line-110"></a> <span class='hs-conid'>Delayed</span>
<a name="line-111"></a> <span class='hs-layout'>{</span> <span class='hs-varid'>serverD</span> <span class='hs-keyglyph'>=</span> <span class='hs-keyglyph'>\</span> <span class='hs-varid'>c</span> <span class='hs-varid'>a</span> <span class='hs-varid'>b</span> <span class='hs-varid'>req</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>f</span> <span class='hs-varop'><$></span> <span class='hs-varid'>serverD</span> <span class='hs-varid'>c</span> <span class='hs-varid'>a</span> <span class='hs-varid'>b</span> <span class='hs-varid'>req</span>
<a name="line-112"></a> <span class='hs-layout'>,</span> <span class='hs-keyglyph'>..</span>
<a name="line-113"></a> <span class='hs-layout'>}</span> <span class='hs-comment'>-- Note [Existential Record Update]</span>
<a name="line-114"></a>
<a name="line-115"></a><a name="DelayedIO"></a><span class='hs-comment'>-- | Computations used in a 'Delayed' can depend on the</span>
<a name="line-116"></a><a name="DelayedIO"></a><span class='hs-comment'>-- incoming 'Request', may perform 'IO, and result in a</span>
<a name="line-117"></a><a name="DelayedIO"></a><span class='hs-comment'>-- 'RouteResult, meaning they can either suceed, fail</span>
<a name="line-118"></a><a name="DelayedIO"></a><span class='hs-comment'>-- (with the possibility to recover), or fail fatally.</span>
<a name="line-119"></a><a name="DelayedIO"></a><span class='hs-comment'>--</span>
<a name="line-120"></a><a name="DelayedIO"></a><span class='hs-keyword'>newtype</span> <span class='hs-conid'>DelayedIO</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>DelayedIO</span> <span class='hs-layout'>{</span> <span class='hs-varid'>runDelayedIO</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Request</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>IO</span> <span class='hs-layout'>(</span><span class='hs-conid'>RouteResult</span> <span class='hs-varid'>a</span><span class='hs-layout'>)</span> <span class='hs-layout'>}</span>
<a name="line-121"></a>
<a name="line-122"></a><a name="instance%20Functor%20DelayedIO"></a><span class='hs-keyword'>instance</span> <span class='hs-conid'>Functor</span> <span class='hs-conid'>DelayedIO</span> <span class='hs-keyword'>where</span>
<a name="line-123"></a> <span class='hs-varid'>fmap</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>liftM</span>
<a name="line-124"></a>
<a name="line-125"></a><a name="instance%20Applicative%20DelayedIO"></a><span class='hs-keyword'>instance</span> <span class='hs-conid'>Applicative</span> <span class='hs-conid'>DelayedIO</span> <span class='hs-keyword'>where</span>
<a name="line-126"></a> <span class='hs-varid'>pure</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>return</span>
<a name="line-127"></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-128"></a>
<a name="line-129"></a><a name="instance%20Monad%20DelayedIO"></a><span class='hs-keyword'>instance</span> <span class='hs-conid'>Monad</span> <span class='hs-conid'>DelayedIO</span> <span class='hs-keyword'>where</span>
<a name="line-130"></a> <span class='hs-varid'>return</span> <span class='hs-varid'>x</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>DelayedIO</span> <span class='hs-layout'>(</span><span class='hs-varid'>const</span> <span class='hs-varop'>$</span> <span class='hs-varid'>return</span> <span class='hs-layout'>(</span><span class='hs-conid'>Route</span> <span class='hs-varid'>x</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span>
<a name="line-131"></a> <span class='hs-conid'>DelayedIO</span> <span class='hs-varid'>m</span> <span class='hs-varop'>>>=</span> <span class='hs-varid'>f</span> <span class='hs-keyglyph'>=</span>
<a name="line-132"></a> <span class='hs-conid'>DelayedIO</span> <span class='hs-varop'>$</span> <span class='hs-keyglyph'>\</span> <span class='hs-varid'>req</span> <span class='hs-keyglyph'>-></span> <span class='hs-keyword'>do</span>
<a name="line-133"></a> <span class='hs-varid'>r</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>m</span> <span class='hs-varid'>req</span>
<a name="line-134"></a> <span class='hs-keyword'>case</span> <span class='hs-varid'>r</span> <span class='hs-keyword'>of</span>
<a name="line-135"></a> <span class='hs-conid'>Fail</span> <span class='hs-varid'>e</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>return</span> <span class='hs-varop'>$</span> <span class='hs-conid'>Fail</span> <span class='hs-varid'>e</span>
<a name="line-136"></a> <span class='hs-conid'>FailFatal</span> <span class='hs-varid'>e</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>return</span> <span class='hs-varop'>$</span> <span class='hs-conid'>FailFatal</span> <span class='hs-varid'>e</span>
<a name="line-137"></a> <span class='hs-conid'>Route</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>runDelayedIO</span> <span class='hs-layout'>(</span><span class='hs-varid'>f</span> <span class='hs-varid'>a</span><span class='hs-layout'>)</span> <span class='hs-varid'>req</span>
<a name="line-138"></a>
<a name="line-139"></a><a name="instance%20MonadIO%20DelayedIO"></a><span class='hs-keyword'>instance</span> <span class='hs-conid'>MonadIO</span> <span class='hs-conid'>DelayedIO</span> <span class='hs-keyword'>where</span>
<a name="line-140"></a> <span class='hs-varid'>liftIO</span> <span class='hs-varid'>m</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>DelayedIO</span> <span class='hs-layout'>(</span><span class='hs-varid'>const</span> <span class='hs-varop'>$</span> <span class='hs-conid'>Route</span> <span class='hs-varop'><$></span> <span class='hs-varid'>m</span><span class='hs-layout'>)</span>
<a name="line-141"></a>
<a name="line-142"></a><a name="emptyDelayed"></a><span class='hs-comment'>-- | A 'Delayed' without any stored checks.</span>
<a name="line-143"></a><span class='hs-definition'>emptyDelayed</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>RouteResult</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Delayed</span> <span class='hs-varid'>env</span> <span class='hs-varid'>a</span>
<a name="line-144"></a><span class='hs-definition'>emptyDelayed</span> <span class='hs-varid'>result</span> <span class='hs-keyglyph'>=</span>
<a name="line-145"></a> <span class='hs-conid'>Delayed</span> <span class='hs-layout'>(</span><span class='hs-varid'>const</span> <span class='hs-varid'>r</span><span class='hs-layout'>)</span> <span class='hs-varid'>r</span> <span class='hs-varid'>r</span> <span class='hs-varid'>r</span> <span class='hs-layout'>(</span><span class='hs-keyglyph'>\</span> <span class='hs-keyword'>_</span> <span class='hs-keyword'>_</span> <span class='hs-keyword'>_</span> <span class='hs-keyword'>_</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>result</span><span class='hs-layout'>)</span>
<a name="line-146"></a> <span class='hs-keyword'>where</span>
<a name="line-147"></a> <span class='hs-varid'>r</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>return</span> <span class='hs-conid'>()</span>
<a name="line-148"></a>
<a name="line-149"></a><a name="delayedFail"></a><span class='hs-comment'>-- | Fail with the option to recover.</span>
<a name="line-150"></a><span class='hs-definition'>delayedFail</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>ServantErr</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>DelayedIO</span> <span class='hs-varid'>a</span>
<a name="line-151"></a><span class='hs-definition'>delayedFail</span> <span class='hs-varid'>err</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>DelayedIO</span> <span class='hs-layout'>(</span><span class='hs-varid'>const</span> <span class='hs-varop'>$</span> <span class='hs-varid'>return</span> <span class='hs-varop'>$</span> <span class='hs-conid'>Fail</span> <span class='hs-varid'>err</span><span class='hs-layout'>)</span>
<a name="line-152"></a>
<a name="line-153"></a><a name="delayedFailFatal"></a><span class='hs-comment'>-- | Fail fatally, i.e., without any option to recover.</span>
<a name="line-154"></a><span class='hs-definition'>delayedFailFatal</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>ServantErr</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>DelayedIO</span> <span class='hs-varid'>a</span>
<a name="line-155"></a><span class='hs-definition'>delayedFailFatal</span> <span class='hs-varid'>err</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>DelayedIO</span> <span class='hs-layout'>(</span><span class='hs-varid'>const</span> <span class='hs-varop'>$</span> <span class='hs-varid'>return</span> <span class='hs-varop'>$</span> <span class='hs-conid'>FailFatal</span> <span class='hs-varid'>err</span><span class='hs-layout'>)</span>
<a name="line-156"></a>
<a name="line-157"></a><a name="withRequest"></a><span class='hs-comment'>-- | Gain access to the incoming request.</span>
<a name="line-158"></a><span class='hs-definition'>withRequest</span> <span class='hs-keyglyph'>::</span> <span class='hs-layout'>(</span><span class='hs-conid'>Request</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>DelayedIO</span> <span class='hs-varid'>a</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>DelayedIO</span> <span class='hs-varid'>a</span>
<a name="line-159"></a><span class='hs-definition'>withRequest</span> <span class='hs-varid'>f</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>DelayedIO</span> <span class='hs-layout'>(</span><span class='hs-keyglyph'>\</span> <span class='hs-varid'>req</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>runDelayedIO</span> <span class='hs-layout'>(</span><span class='hs-varid'>f</span> <span class='hs-varid'>req</span><span class='hs-layout'>)</span> <span class='hs-varid'>req</span><span class='hs-layout'>)</span>
<a name="line-160"></a>
<a name="line-161"></a><a name="addCapture"></a><span class='hs-comment'>-- | Add a capture to the end of the capture block.</span>
<a name="line-162"></a><span class='hs-definition'>addCapture</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Delayed</span> <span class='hs-varid'>env</span> <span class='hs-layout'>(</span><span class='hs-varid'>a</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>b</span><span class='hs-layout'>)</span>
<a name="line-163"></a> <span class='hs-keyglyph'>-></span> <span class='hs-layout'>(</span><span class='hs-varid'>captured</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>DelayedIO</span> <span class='hs-varid'>a</span><span class='hs-layout'>)</span>
<a name="line-164"></a> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Delayed</span> <span class='hs-layout'>(</span><span class='hs-varid'>captured</span><span class='hs-layout'>,</span> <span class='hs-varid'>env</span><span class='hs-layout'>)</span> <span class='hs-varid'>b</span>
<a name="line-165"></a><span class='hs-definition'>addCapture</span> <span class='hs-conid'>Delayed</span><span class='hs-layout'>{</span><span class='hs-keyglyph'>..</span><span class='hs-layout'>}</span> <span class='hs-varid'>new</span> <span class='hs-keyglyph'>=</span>
<a name="line-166"></a> <span class='hs-conid'>Delayed</span>
<a name="line-167"></a> <span class='hs-layout'>{</span> <span class='hs-varid'>capturesD</span> <span class='hs-keyglyph'>=</span> <span class='hs-keyglyph'>\</span> <span class='hs-layout'>(</span><span class='hs-varid'>txt</span><span class='hs-layout'>,</span> <span class='hs-varid'>env</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>(,)</span> <span class='hs-varop'><$></span> <span class='hs-varid'>capturesD</span> <span class='hs-varid'>env</span> <span class='hs-varop'><*></span> <span class='hs-varid'>new</span> <span class='hs-varid'>txt</span>
<a name="line-168"></a> <span class='hs-layout'>,</span> <span class='hs-varid'>serverD</span> <span class='hs-keyglyph'>=</span> <span class='hs-keyglyph'>\</span> <span class='hs-layout'>(</span><span class='hs-varid'>x</span><span class='hs-layout'>,</span> <span class='hs-varid'>v</span><span class='hs-layout'>)</span> <span class='hs-varid'>a</span> <span class='hs-varid'>b</span> <span class='hs-varid'>req</span> <span class='hs-keyglyph'>-></span> <span class='hs-layout'>(</span><span class='hs-varop'>$</span> <span class='hs-varid'>v</span><span class='hs-layout'>)</span> <span class='hs-varop'><$></span> <span class='hs-varid'>serverD</span> <span class='hs-varid'>x</span> <span class='hs-varid'>a</span> <span class='hs-varid'>b</span> <span class='hs-varid'>req</span>
<a name="line-169"></a> <span class='hs-layout'>,</span> <span class='hs-keyglyph'>..</span>
<a name="line-170"></a> <span class='hs-layout'>}</span> <span class='hs-comment'>-- Note [Existential Record Update]</span>
<a name="line-171"></a>
<a name="line-172"></a><a name="addMethodCheck"></a><span class='hs-comment'>-- | Add a method check to the end of the method block.</span>
<a name="line-173"></a><span class='hs-definition'>addMethodCheck</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Delayed</span> <span class='hs-varid'>env</span> <span class='hs-varid'>a</span>
<a name="line-174"></a> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>DelayedIO</span> <span class='hs-conid'>()</span>
<a name="line-175"></a> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Delayed</span> <span class='hs-varid'>env</span> <span class='hs-varid'>a</span>
<a name="line-176"></a><span class='hs-definition'>addMethodCheck</span> <span class='hs-conid'>Delayed</span><span class='hs-layout'>{</span><span class='hs-keyglyph'>..</span><span class='hs-layout'>}</span> <span class='hs-varid'>new</span> <span class='hs-keyglyph'>=</span>
<a name="line-177"></a> <span class='hs-conid'>Delayed</span>
<a name="line-178"></a> <span class='hs-layout'>{</span> <span class='hs-varid'>methodD</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>methodD</span> <span class='hs-varop'><*</span> <span class='hs-varid'>new</span>
<a name="line-179"></a> <span class='hs-layout'>,</span> <span class='hs-keyglyph'>..</span>
<a name="line-180"></a> <span class='hs-layout'>}</span> <span class='hs-comment'>-- Note [Existential Record Update]</span>
<a name="line-181"></a>
<a name="line-182"></a><a name="addAuthCheck"></a><span class='hs-comment'>-- | Add an auth check to the end of the auth block.</span>
<a name="line-183"></a><span class='hs-definition'>addAuthCheck</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Delayed</span> <span class='hs-varid'>env</span> <span class='hs-layout'>(</span><span class='hs-varid'>a</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>b</span><span class='hs-layout'>)</span>
<a name="line-184"></a> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>DelayedIO</span> <span class='hs-varid'>a</span>
<a name="line-185"></a> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Delayed</span> <span class='hs-varid'>env</span> <span class='hs-varid'>b</span>
<a name="line-186"></a><span class='hs-definition'>addAuthCheck</span> <span class='hs-conid'>Delayed</span><span class='hs-layout'>{</span><span class='hs-keyglyph'>..</span><span class='hs-layout'>}</span> <span class='hs-varid'>new</span> <span class='hs-keyglyph'>=</span>
<a name="line-187"></a> <span class='hs-conid'>Delayed</span>
<a name="line-188"></a> <span class='hs-layout'>{</span> <span class='hs-varid'>authD</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>(,)</span> <span class='hs-varop'><$></span> <span class='hs-varid'>authD</span> <span class='hs-varop'><*></span> <span class='hs-varid'>new</span>
<a name="line-189"></a> <span class='hs-layout'>,</span> <span class='hs-varid'>serverD</span> <span class='hs-keyglyph'>=</span> <span class='hs-keyglyph'>\</span> <span class='hs-varid'>c</span> <span class='hs-layout'>(</span><span class='hs-varid'>y</span><span class='hs-layout'>,</span> <span class='hs-varid'>v</span><span class='hs-layout'>)</span> <span class='hs-varid'>b</span> <span class='hs-varid'>req</span> <span class='hs-keyglyph'>-></span> <span class='hs-layout'>(</span><span class='hs-varop'>$</span> <span class='hs-varid'>v</span><span class='hs-layout'>)</span> <span class='hs-varop'><$></span> <span class='hs-varid'>serverD</span> <span class='hs-varid'>c</span> <span class='hs-varid'>y</span> <span class='hs-varid'>b</span> <span class='hs-varid'>req</span>
<a name="line-190"></a> <span class='hs-layout'>,</span> <span class='hs-keyglyph'>..</span>
<a name="line-191"></a> <span class='hs-layout'>}</span> <span class='hs-comment'>-- Note [Existential Record Update]</span>
<a name="line-192"></a>
<a name="line-193"></a><a name="addBodyCheck"></a><span class='hs-comment'>-- | Add a body check to the end of the body block.</span>
<a name="line-194"></a><span class='hs-definition'>addBodyCheck</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Delayed</span> <span class='hs-varid'>env</span> <span class='hs-layout'>(</span><span class='hs-varid'>a</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>b</span><span class='hs-layout'>)</span>
<a name="line-195"></a> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>DelayedIO</span> <span class='hs-varid'>a</span>
<a name="line-196"></a> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Delayed</span> <span class='hs-varid'>env</span> <span class='hs-varid'>b</span>
<a name="line-197"></a><span class='hs-definition'>addBodyCheck</span> <span class='hs-conid'>Delayed</span><span class='hs-layout'>{</span><span class='hs-keyglyph'>..</span><span class='hs-layout'>}</span> <span class='hs-varid'>new</span> <span class='hs-keyglyph'>=</span>
<a name="line-198"></a> <span class='hs-conid'>Delayed</span>
<a name="line-199"></a> <span class='hs-layout'>{</span> <span class='hs-varid'>bodyD</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>(,)</span> <span class='hs-varop'><$></span> <span class='hs-varid'>bodyD</span> <span class='hs-varop'><*></span> <span class='hs-varid'>new</span>
<a name="line-200"></a> <span class='hs-layout'>,</span> <span class='hs-varid'>serverD</span> <span class='hs-keyglyph'>=</span> <span class='hs-keyglyph'>\</span> <span class='hs-varid'>c</span> <span class='hs-varid'>a</span> <span class='hs-layout'>(</span><span class='hs-varid'>z</span><span class='hs-layout'>,</span> <span class='hs-varid'>v</span><span class='hs-layout'>)</span> <span class='hs-varid'>req</span> <span class='hs-keyglyph'>-></span> <span class='hs-layout'>(</span><span class='hs-varop'>$</span> <span class='hs-varid'>v</span><span class='hs-layout'>)</span> <span class='hs-varop'><$></span> <span class='hs-varid'>serverD</span> <span class='hs-varid'>c</span> <span class='hs-varid'>a</span> <span class='hs-varid'>z</span> <span class='hs-varid'>req</span>
<a name="line-201"></a> <span class='hs-layout'>,</span> <span class='hs-keyglyph'>..</span>
<a name="line-202"></a> <span class='hs-layout'>}</span> <span class='hs-comment'>-- Note [Existential Record Update]</span>
<a name="line-203"></a>
<a name="line-204"></a>
<a name="line-205"></a><a name="addAcceptCheck"></a><span class='hs-comment'>-- | Add an accept header check to the beginning of the body</span>
<a name="line-206"></a><span class='hs-comment'>-- block. There is a tradeoff here. In principle, we'd like</span>
<a name="line-207"></a><span class='hs-comment'>-- to take a bad body (400) response take precedence over a</span>
<a name="line-208"></a><span class='hs-comment'>-- failed accept check (406). BUT to allow streaming the body,</span>
<a name="line-209"></a><span class='hs-comment'>-- we cannot run the body check and then still backtrack.</span>
<a name="line-210"></a><span class='hs-comment'>-- We therefore do the accept check before the body check,</span>
<a name="line-211"></a><span class='hs-comment'>-- when we can still backtrack. There are other solutions to</span>
<a name="line-212"></a><span class='hs-comment'>-- this, but they'd be more complicated (such as delaying the</span>
<a name="line-213"></a><span class='hs-comment'>-- body check further so that it can still be run in a situation</span>
<a name="line-214"></a><span class='hs-comment'>-- where we'd otherwise report 406).</span>
<a name="line-215"></a><span class='hs-definition'>addAcceptCheck</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Delayed</span> <span class='hs-varid'>env</span> <span class='hs-varid'>a</span>
<a name="line-216"></a> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>DelayedIO</span> <span class='hs-conid'>()</span>
<a name="line-217"></a> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Delayed</span> <span class='hs-varid'>env</span> <span class='hs-varid'>a</span>
<a name="line-218"></a><span class='hs-definition'>addAcceptCheck</span> <span class='hs-conid'>Delayed</span><span class='hs-layout'>{</span><span class='hs-keyglyph'>..</span><span class='hs-layout'>}</span> <span class='hs-varid'>new</span> <span class='hs-keyglyph'>=</span>
<a name="line-219"></a> <span class='hs-conid'>Delayed</span>
<a name="line-220"></a> <span class='hs-layout'>{</span> <span class='hs-varid'>bodyD</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>new</span> <span class='hs-varop'>*></span> <span class='hs-varid'>bodyD</span>
<a name="line-221"></a> <span class='hs-layout'>,</span> <span class='hs-keyglyph'>..</span>
<a name="line-222"></a> <span class='hs-layout'>}</span> <span class='hs-comment'>-- Note [Existential Record Update]</span>
<a name="line-223"></a>
<a name="line-224"></a><a name="passToServer"></a><span class='hs-comment'>-- | Many combinators extract information that is passed to</span>
<a name="line-225"></a><span class='hs-comment'>-- the handler without the possibility of failure. In such a</span>
<a name="line-226"></a><span class='hs-comment'>-- case, 'passToServer' can be used.</span>
<a name="line-227"></a><span class='hs-definition'>passToServer</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Delayed</span> <span class='hs-varid'>env</span> <span class='hs-layout'>(</span><span class='hs-varid'>a</span> <span class='hs-keyglyph'>-></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-conid'>Request</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>a</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Delayed</span> <span class='hs-varid'>env</span> <span class='hs-varid'>b</span>
<a name="line-228"></a><span class='hs-definition'>passToServer</span> <span class='hs-conid'>Delayed</span><span class='hs-layout'>{</span><span class='hs-keyglyph'>..</span><span class='hs-layout'>}</span> <span class='hs-varid'>x</span> <span class='hs-keyglyph'>=</span>
<a name="line-229"></a> <span class='hs-conid'>Delayed</span>
<a name="line-230"></a> <span class='hs-layout'>{</span> <span class='hs-varid'>serverD</span> <span class='hs-keyglyph'>=</span> <span class='hs-keyglyph'>\</span> <span class='hs-varid'>c</span> <span class='hs-varid'>a</span> <span class='hs-varid'>b</span> <span class='hs-varid'>req</span> <span class='hs-keyglyph'>-></span> <span class='hs-layout'>(</span><span class='hs-varop'>$</span> <span class='hs-varid'>x</span> <span class='hs-varid'>req</span><span class='hs-layout'>)</span> <span class='hs-varop'><$></span> <span class='hs-varid'>serverD</span> <span class='hs-varid'>c</span> <span class='hs-varid'>a</span> <span class='hs-varid'>b</span> <span class='hs-varid'>req</span>
<a name="line-231"></a> <span class='hs-layout'>,</span> <span class='hs-keyglyph'>..</span>
<a name="line-232"></a> <span class='hs-layout'>}</span> <span class='hs-comment'>-- Note [Existential Record Update]</span>
<a name="line-233"></a>
<a name="line-234"></a><a name="runDelayed"></a><span class='hs-comment'>-- | Run a delayed server. Performs all scheduled operations</span>
<a name="line-235"></a><span class='hs-comment'>-- in order, and passes the results from the capture and body</span>
<a name="line-236"></a><span class='hs-comment'>-- blocks on to the actual handler.</span>
<a name="line-237"></a><span class='hs-comment'>--</span>
<a name="line-238"></a><span class='hs-comment'>-- This should only be called once per request; otherwise the guarantees about</span>
<a name="line-239"></a><span class='hs-comment'>-- effect and HTTP error ordering break down.</span>
<a name="line-240"></a><span class='hs-definition'>runDelayed</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Delayed</span> <span class='hs-varid'>env</span> <span class='hs-varid'>a</span>
<a name="line-241"></a> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>env</span>
<a name="line-242"></a> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Request</span>
<a name="line-243"></a> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>IO</span> <span class='hs-layout'>(</span><span class='hs-conid'>RouteResult</span> <span class='hs-varid'>a</span><span class='hs-layout'>)</span>
<a name="line-244"></a><span class='hs-definition'>runDelayed</span> <span class='hs-conid'>Delayed</span><span class='hs-layout'>{</span><span class='hs-keyglyph'>..</span><span class='hs-layout'>}</span> <span class='hs-varid'>env</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>runDelayedIO</span> <span class='hs-varop'>$</span> <span class='hs-keyword'>do</span>
<a name="line-245"></a> <span class='hs-varid'>c</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>capturesD</span> <span class='hs-varid'>env</span>
<a name="line-246"></a> <span class='hs-varid'>methodD</span>
<a name="line-247"></a> <span class='hs-varid'>a</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>authD</span>
<a name="line-248"></a> <span class='hs-varid'>b</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>bodyD</span>
<a name="line-249"></a> <span class='hs-conid'>DelayedIO</span> <span class='hs-layout'>(</span><span class='hs-keyglyph'>\</span> <span class='hs-varid'>req</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>return</span> <span class='hs-varop'>$</span> <span class='hs-varid'>serverD</span> <span class='hs-varid'>c</span> <span class='hs-varid'>a</span> <span class='hs-varid'>b</span> <span class='hs-varid'>req</span><span class='hs-layout'>)</span>
<a name="line-250"></a>
<a name="line-251"></a><a name="runAction"></a><span class='hs-comment'>-- | Runs a delayed server and the resulting action.</span>
<a name="line-252"></a><span class='hs-comment'>-- Takes a continuation that lets us send a response.</span>
<a name="line-253"></a><span class='hs-comment'>-- Also takes a continuation for how to turn the</span>
<a name="line-254"></a><span class='hs-comment'>-- result of the delayed server into a response.</span>
<a name="line-255"></a><span class='hs-definition'>runAction</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Delayed</span> <span class='hs-varid'>env</span> <span class='hs-layout'>(</span><span class='hs-conid'>Handler</span> <span class='hs-varid'>a</span><span class='hs-layout'>)</span>
<a name="line-256"></a> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>env</span>
<a name="line-257"></a> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Request</span>
<a name="line-258"></a> <span class='hs-keyglyph'>-></span> <span class='hs-layout'>(</span><span class='hs-conid'>RouteResult</span> <span class='hs-conid'>Response</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>IO</span> <span class='hs-varid'>r</span><span class='hs-layout'>)</span>
<a name="line-259"></a> <span class='hs-keyglyph'>-></span> <span class='hs-layout'>(</span><span class='hs-varid'>a</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>RouteResult</span> <span class='hs-conid'>Response</span><span class='hs-layout'>)</span>
<a name="line-260"></a> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>IO</span> <span class='hs-varid'>r</span>
<a name="line-261"></a><span class='hs-definition'>runAction</span> <span class='hs-varid'>action</span> <span class='hs-varid'>env</span> <span class='hs-varid'>req</span> <span class='hs-varid'>respond</span> <span class='hs-varid'>k</span> <span class='hs-keyglyph'>=</span>
<a name="line-262"></a> <span class='hs-varid'>runDelayed</span> <span class='hs-varid'>action</span> <span class='hs-varid'>env</span> <span class='hs-varid'>req</span> <span class='hs-varop'>>>=</span> <span class='hs-varid'>go</span> <span class='hs-varop'>>>=</span> <span class='hs-varid'>respond</span>
<a name="line-263"></a> <span class='hs-keyword'>where</span>
<a name="line-264"></a> <span class='hs-varid'>go</span> <span class='hs-layout'>(</span><span class='hs-conid'>Fail</span> <span class='hs-varid'>e</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>return</span> <span class='hs-varop'>$</span> <span class='hs-conid'>Fail</span> <span class='hs-varid'>e</span>
<a name="line-265"></a> <span class='hs-varid'>go</span> <span class='hs-layout'>(</span><span class='hs-conid'>FailFatal</span> <span class='hs-varid'>e</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>return</span> <span class='hs-varop'>$</span> <span class='hs-conid'>FailFatal</span> <span class='hs-varid'>e</span>
<a name="line-266"></a> <span class='hs-varid'>go</span> <span class='hs-layout'>(</span><span class='hs-conid'>Route</span> <span class='hs-varid'>a</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-keyword'>do</span>
<a name="line-267"></a> <span class='hs-varid'>e</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>runExceptT</span> <span class='hs-varid'>a</span>
<a name="line-268"></a> <span class='hs-keyword'>case</span> <span class='hs-varid'>e</span> <span class='hs-keyword'>of</span>
<a name="line-269"></a> <span class='hs-conid'>Left</span> <span class='hs-varid'>err</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>return</span> <span class='hs-varop'>.</span> <span class='hs-conid'>Route</span> <span class='hs-varop'>$</span> <span class='hs-varid'>responseServantErr</span> <span class='hs-varid'>err</span>
<a name="line-270"></a> <span class='hs-conid'>Right</span> <span class='hs-varid'>x</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>return</span> <span class='hs-varop'>$!</span> <span class='hs-varid'>k</span> <span class='hs-varid'>x</span>
<a name="line-271"></a>
<a name="line-272"></a><span class='hs-comment'>{- Note [Existential Record Update]
<a name="line-273"></a>~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
<a name="line-274"></a>
<a name="line-275"></a>Due to GHC issue <https://ghc.haskell.org/trac/ghc/ticket/2595 2595>, we cannot
<a name="line-276"></a>do the more succint thing - just update the records we actually change.
<a name="line-277"></a>-}</span>
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