<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html>
<head>
<!-- Generated by HsColour, http://www.cs.york.ac.uk/fp/darcs/hscolour/ -->
<title>utils/IOEnv.hs</title>
<link type='text/css' rel='stylesheet' href='hscolour.css' />
</head>
<body>
<pre><a name="line-1"></a><span class='hs-comment'>--</span>
<a name="line-2"></a><span class='hs-comment'>-- (c) The University of Glasgow 2002-2006</span>
<a name="line-3"></a><span class='hs-comment'>--</span>
<a name="line-4"></a><span class='hs-comment'>-- The IO Monad with an environment</span>
<a name="line-5"></a><span class='hs-comment'>--</span>
<a name="line-6"></a><span class='hs-comment'>{-# LANGUAGE UndecidableInstances #-}</span>
<a name="line-7"></a>
<a name="line-8"></a><span class='hs-keyword'>module</span> <span class='hs-conid'>IOEnv</span> <span class='hs-layout'>(</span>
<a name="line-9"></a> <span class='hs-conid'>IOEnv</span><span class='hs-layout'>,</span> <span class='hs-comment'>-- Instance of Monad</span>
<a name="line-10"></a>
<a name="line-11"></a> <span class='hs-comment'>-- Monad utilities</span>
<a name="line-12"></a> <span class='hs-keyword'>module</span> <span class='hs-conid'>MonadUtils</span><span class='hs-layout'>,</span>
<a name="line-13"></a>
<a name="line-14"></a> <span class='hs-comment'>-- Errors</span>
<a name="line-15"></a> <span class='hs-varid'>failM</span><span class='hs-layout'>,</span> <span class='hs-varid'>failWithM</span><span class='hs-layout'>,</span>
<a name="line-16"></a> <span class='hs-conid'>IOEnvFailure</span><span class='hs-layout'>(</span><span class='hs-keyglyph'>..</span><span class='hs-layout'>)</span><span class='hs-layout'>,</span>
<a name="line-17"></a>
<a name="line-18"></a> <span class='hs-comment'>-- Getting at the environment</span>
<a name="line-19"></a> <span class='hs-varid'>getEnv</span><span class='hs-layout'>,</span> <span class='hs-varid'>setEnv</span><span class='hs-layout'>,</span> <span class='hs-varid'>updEnv</span><span class='hs-layout'>,</span>
<a name="line-20"></a>
<a name="line-21"></a> <span class='hs-varid'>runIOEnv</span><span class='hs-layout'>,</span> <span class='hs-varid'>unsafeInterleaveM</span><span class='hs-layout'>,</span>
<a name="line-22"></a> <span class='hs-varid'>tryM</span><span class='hs-layout'>,</span> <span class='hs-varid'>tryAllM</span><span class='hs-layout'>,</span> <span class='hs-varid'>tryMostM</span><span class='hs-layout'>,</span> <span class='hs-varid'>fixM</span><span class='hs-layout'>,</span>
<a name="line-23"></a>
<a name="line-24"></a> <span class='hs-comment'>-- I/O operations</span>
<a name="line-25"></a> <span class='hs-conid'>IORef</span><span class='hs-layout'>,</span> <span class='hs-varid'>newMutVar</span><span class='hs-layout'>,</span> <span class='hs-varid'>readMutVar</span><span class='hs-layout'>,</span> <span class='hs-varid'>writeMutVar</span><span class='hs-layout'>,</span> <span class='hs-varid'>updMutVar</span><span class='hs-layout'>,</span>
<a name="line-26"></a> <span class='hs-varid'>atomicUpdMutVar</span><span class='hs-layout'>,</span> <span class='hs-varid'>atomicUpdMutVar'</span>
<a name="line-27"></a> <span class='hs-layout'>)</span> <span class='hs-keyword'>where</span>
<a name="line-28"></a>
<a name="line-29"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Exception</span>
<a name="line-30"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Panic</span>
<a name="line-31"></a>
<a name="line-32"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Data</span><span class='hs-varop'>.</span><span class='hs-conid'>IORef</span> <span class='hs-layout'>(</span> <span class='hs-conid'>IORef</span><span class='hs-layout'>,</span> <span class='hs-varid'>newIORef</span><span class='hs-layout'>,</span> <span class='hs-varid'>readIORef</span><span class='hs-layout'>,</span> <span class='hs-varid'>writeIORef</span><span class='hs-layout'>,</span> <span class='hs-varid'>modifyIORef</span><span class='hs-layout'>,</span>
<a name="line-33"></a> <span class='hs-varid'>atomicModifyIORef</span> <span class='hs-layout'>)</span>
<a name="line-34"></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-35"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>System</span><span class='hs-varop'>.</span><span class='hs-conid'>IO</span><span class='hs-varop'>.</span><span class='hs-conid'>Unsafe</span> <span class='hs-layout'>(</span> <span class='hs-varid'>unsafeInterleaveIO</span> <span class='hs-layout'>)</span>
<a name="line-36"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>System</span><span class='hs-varop'>.</span><span class='hs-conid'>IO</span> <span class='hs-layout'>(</span> <span class='hs-varid'>fixIO</span> <span class='hs-layout'>)</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'>MonadUtils</span>
<a name="line-39"></a>
<a name="line-40"></a><span class='hs-comment'>----------------------------------------------------------------------</span>
<a name="line-41"></a><span class='hs-comment'>-- Defining the monad type</span>
<a name="line-42"></a><span class='hs-comment'>----------------------------------------------------------------------</span>
<a name="line-43"></a>
<a name="line-44"></a>
<a name="line-45"></a><a name="IOEnv"></a><span class='hs-keyword'>newtype</span> <span class='hs-conid'>IOEnv</span> <span class='hs-varid'>env</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>IOEnv</span> <span class='hs-layout'>(</span><span class='hs-varid'>env</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>IO</span> <span class='hs-varid'>a</span><span class='hs-layout'>)</span>
<a name="line-46"></a>
<a name="line-47"></a><a name="unIOEnv"></a><span class='hs-definition'>unIOEnv</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>IOEnv</span> <span class='hs-varid'>env</span> <span class='hs-varid'>a</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-conid'>IO</span> <span class='hs-varid'>a</span><span class='hs-layout'>)</span>
<a name="line-48"></a><span class='hs-definition'>unIOEnv</span> <span class='hs-layout'>(</span><span class='hs-conid'>IOEnv</span> <span class='hs-varid'>m</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>m</span>
<a name="line-49"></a>
<a name="line-50"></a><span class='hs-keyword'>instance</span> <span class='hs-conid'>Monad</span> <span class='hs-layout'>(</span><span class='hs-conid'>IOEnv</span> <span class='hs-varid'>m</span><span class='hs-layout'>)</span> <span class='hs-keyword'>where</span>
<a name="line-51"></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'>thenM</span>
<a name="line-52"></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'>thenM_</span>
<a name="line-53"></a> <span class='hs-varid'>return</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>returnM</span>
<a name="line-54"></a> <span class='hs-varid'>fail</span> <span class='hs-keyword'>_</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>failM</span> <span class='hs-comment'>-- Ignore the string</span>
<a name="line-55"></a>
<a name="line-56"></a><span class='hs-keyword'>instance</span> <span class='hs-conid'>Applicative</span> <span class='hs-layout'>(</span><span class='hs-conid'>IOEnv</span> <span class='hs-varid'>m</span><span class='hs-layout'>)</span> <span class='hs-keyword'>where</span>
<a name="line-57"></a> <span class='hs-varid'>pure</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>returnM</span>
<a name="line-58"></a> <span class='hs-conid'>IOEnv</span> <span class='hs-varid'>f</span> <span class='hs-varop'><*></span> <span class='hs-conid'>IOEnv</span> <span class='hs-varid'>x</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>IOEnv</span> <span class='hs-layout'>(</span><span class='hs-keyglyph'>\</span> <span class='hs-varid'>env</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>f</span> <span class='hs-varid'>env</span> <span class='hs-varop'><*></span> <span class='hs-varid'>x</span> <span class='hs-varid'>env</span> <span class='hs-layout'>)</span>
<a name="line-59"></a>
<a name="line-60"></a><span class='hs-keyword'>instance</span> <span class='hs-conid'>Functor</span> <span class='hs-layout'>(</span><span class='hs-conid'>IOEnv</span> <span class='hs-varid'>m</span><span class='hs-layout'>)</span> <span class='hs-keyword'>where</span>
<a name="line-61"></a> <span class='hs-varid'>fmap</span> <span class='hs-varid'>f</span> <span class='hs-layout'>(</span><span class='hs-conid'>IOEnv</span> <span class='hs-varid'>m</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>IOEnv</span> <span class='hs-layout'>(</span><span class='hs-keyglyph'>\</span> <span class='hs-varid'>env</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>fmap</span> <span class='hs-varid'>f</span> <span class='hs-layout'>(</span><span class='hs-varid'>m</span> <span class='hs-varid'>env</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span>
<a name="line-62"></a>
<a name="line-63"></a><a name="returnM"></a><span class='hs-definition'>returnM</span> <span class='hs-keyglyph'>::</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>IOEnv</span> <span class='hs-varid'>env</span> <span class='hs-varid'>a</span>
<a name="line-64"></a><span class='hs-definition'>returnM</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>IOEnv</span> <span class='hs-layout'>(</span><span class='hs-keyglyph'>\</span> <span class='hs-keyword'>_</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>return</span> <span class='hs-varid'>a</span><span class='hs-layout'>)</span>
<a name="line-65"></a>
<a name="line-66"></a><a name="thenM"></a><span class='hs-definition'>thenM</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>IOEnv</span> <span class='hs-varid'>env</span> <span class='hs-varid'>a</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-conid'>IOEnv</span> <span class='hs-varid'>env</span> <span class='hs-varid'>b</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>IOEnv</span> <span class='hs-varid'>env</span> <span class='hs-varid'>b</span>
<a name="line-67"></a><span class='hs-definition'>thenM</span> <span class='hs-layout'>(</span><span class='hs-conid'>IOEnv</span> <span class='hs-varid'>m</span><span class='hs-layout'>)</span> <span class='hs-varid'>f</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>IOEnv</span> <span class='hs-layout'>(</span><span class='hs-keyglyph'>\</span> <span class='hs-varid'>env</span> <span class='hs-keyglyph'>-></span> <span class='hs-keyword'>do</span> <span class='hs-layout'>{</span> <span class='hs-varid'>r</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>m</span> <span class='hs-varid'>env</span> <span class='hs-layout'>;</span>
<a name="line-68"></a> <span class='hs-varid'>unIOEnv</span> <span class='hs-layout'>(</span><span class='hs-varid'>f</span> <span class='hs-varid'>r</span><span class='hs-layout'>)</span> <span class='hs-varid'>env</span> <span class='hs-layout'>}</span><span class='hs-layout'>)</span>
<a name="line-69"></a>
<a name="line-70"></a><a name="thenM_"></a><span class='hs-definition'>thenM_</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>IOEnv</span> <span class='hs-varid'>env</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>IOEnv</span> <span class='hs-varid'>env</span> <span class='hs-varid'>b</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>IOEnv</span> <span class='hs-varid'>env</span> <span class='hs-varid'>b</span>
<a name="line-71"></a><span class='hs-definition'>thenM_</span> <span class='hs-layout'>(</span><span class='hs-conid'>IOEnv</span> <span class='hs-varid'>m</span><span class='hs-layout'>)</span> <span class='hs-varid'>f</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>IOEnv</span> <span class='hs-layout'>(</span><span class='hs-keyglyph'>\</span> <span class='hs-varid'>env</span> <span class='hs-keyglyph'>-></span> <span class='hs-keyword'>do</span> <span class='hs-layout'>{</span> <span class='hs-keyword'>_</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>m</span> <span class='hs-varid'>env</span> <span class='hs-layout'>;</span> <span class='hs-varid'>unIOEnv</span> <span class='hs-varid'>f</span> <span class='hs-varid'>env</span> <span class='hs-layout'>}</span><span class='hs-layout'>)</span>
<a name="line-72"></a>
<a name="line-73"></a><a name="failM"></a><span class='hs-definition'>failM</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>IOEnv</span> <span class='hs-varid'>env</span> <span class='hs-varid'>a</span>
<a name="line-74"></a><span class='hs-definition'>failM</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>IOEnv</span> <span class='hs-layout'>(</span><span class='hs-keyglyph'>\</span> <span class='hs-keyword'>_</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>throwIO</span> <span class='hs-conid'>IOEnvFailure</span><span class='hs-layout'>)</span>
<a name="line-75"></a>
<a name="line-76"></a><a name="failWithM"></a><span class='hs-definition'>failWithM</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>String</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>IOEnv</span> <span class='hs-varid'>env</span> <span class='hs-varid'>a</span>
<a name="line-77"></a><span class='hs-definition'>failWithM</span> <span class='hs-varid'>s</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>IOEnv</span> <span class='hs-layout'>(</span><span class='hs-keyglyph'>\</span> <span class='hs-keyword'>_</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>ioError</span> <span class='hs-layout'>(</span><span class='hs-varid'>userError</span> <span class='hs-varid'>s</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span>
<a name="line-78"></a>
<a name="line-79"></a><a name="IOEnvFailure"></a><span class='hs-keyword'>data</span> <span class='hs-conid'>IOEnvFailure</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>IOEnvFailure</span>
<a name="line-80"></a> <span class='hs-keyword'>deriving</span> <span class='hs-conid'>Typeable</span>
<a name="line-81"></a>
<a name="line-82"></a><span class='hs-keyword'>instance</span> <span class='hs-conid'>Show</span> <span class='hs-conid'>IOEnvFailure</span> <span class='hs-keyword'>where</span>
<a name="line-83"></a> <span class='hs-varid'>show</span> <span class='hs-conid'>IOEnvFailure</span> <span class='hs-keyglyph'>=</span> <span class='hs-str'>"IOEnv failure"</span>
<a name="line-84"></a>
<a name="line-85"></a><span class='hs-keyword'>instance</span> <span class='hs-conid'>Exception</span> <span class='hs-conid'>IOEnvFailure</span>
<a name="line-86"></a>
<a name="line-87"></a><span class='hs-comment'>----------------------------------------------------------------------</span>
<a name="line-88"></a><span class='hs-comment'>-- Fundmantal combinators specific to the monad</span>
<a name="line-89"></a><span class='hs-comment'>----------------------------------------------------------------------</span>
<a name="line-90"></a>
<a name="line-91"></a>
<a name="line-92"></a><a name="runIOEnv"></a><span class='hs-comment'>---------------------------</span>
<a name="line-93"></a><span class='hs-definition'>runIOEnv</span> <span class='hs-keyglyph'>::</span> <span class='hs-varid'>env</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>IOEnv</span> <span class='hs-varid'>env</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>IO</span> <span class='hs-varid'>a</span>
<a name="line-94"></a><span class='hs-definition'>runIOEnv</span> <span class='hs-varid'>env</span> <span class='hs-layout'>(</span><span class='hs-conid'>IOEnv</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-varid'>env</span>
<a name="line-95"></a>
<a name="line-96"></a>
<a name="line-97"></a><span class='hs-comment'>---------------------------</span>
<a name="line-98"></a><span class='hs-comment'>{-# NOINLINE fixM #-}</span>
<a name="line-99"></a> <span class='hs-comment'>-- Aargh! Not inlining fixTc alleviates a space leak problem.</span>
<a name="line-100"></a> <span class='hs-comment'>-- Normally fixTc is used with a lazy tuple match: if the optimiser is</span>
<a name="line-101"></a> <span class='hs-comment'>-- shown the definition of fixTc, it occasionally transforms the code</span>
<a name="line-102"></a> <span class='hs-comment'>-- in such a way that the code generator doesn't spot the selector</span>
<a name="line-103"></a> <span class='hs-comment'>-- thunks. Sigh.</span>
<a name="line-104"></a>
<a name="line-105"></a><a name="fixM"></a><span class='hs-definition'>fixM</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-conid'>IOEnv</span> <span class='hs-varid'>env</span> <span class='hs-varid'>a</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>IOEnv</span> <span class='hs-varid'>env</span> <span class='hs-varid'>a</span>
<a name="line-106"></a><span class='hs-definition'>fixM</span> <span class='hs-varid'>f</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>IOEnv</span> <span class='hs-layout'>(</span><span class='hs-keyglyph'>\</span> <span class='hs-varid'>env</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>fixIO</span> <span class='hs-layout'>(</span><span class='hs-keyglyph'>\</span> <span class='hs-varid'>r</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>unIOEnv</span> <span class='hs-layout'>(</span><span class='hs-varid'>f</span> <span class='hs-varid'>r</span><span class='hs-layout'>)</span> <span class='hs-varid'>env</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span>
<a name="line-107"></a>
<a name="line-108"></a>
<a name="line-109"></a><a name="tryM"></a><span class='hs-comment'>---------------------------</span>
<a name="line-110"></a><span class='hs-definition'>tryM</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>IOEnv</span> <span class='hs-varid'>env</span> <span class='hs-varid'>r</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>IOEnv</span> <span class='hs-varid'>env</span> <span class='hs-layout'>(</span><span class='hs-conid'>Either</span> <span class='hs-conid'>IOEnvFailure</span> <span class='hs-varid'>r</span><span class='hs-layout'>)</span>
<a name="line-111"></a><span class='hs-comment'>-- Reflect UserError exceptions (only) into IOEnv monad</span>
<a name="line-112"></a><span class='hs-comment'>-- Other exceptions are not caught; they are simply propagated as exns</span>
<a name="line-113"></a><span class='hs-comment'>--</span>
<a name="line-114"></a><span class='hs-comment'>-- The idea is that errors in the program being compiled will give rise</span>
<a name="line-115"></a><span class='hs-comment'>-- to UserErrors. But, say, pattern-match failures in GHC itself should</span>
<a name="line-116"></a><span class='hs-comment'>-- not be caught here, else they'll be reported as errors in the program</span>
<a name="line-117"></a><span class='hs-comment'>-- begin compiled!</span>
<a name="line-118"></a><span class='hs-definition'>tryM</span> <span class='hs-layout'>(</span><span class='hs-conid'>IOEnv</span> <span class='hs-varid'>thing</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>IOEnv</span> <span class='hs-layout'>(</span><span class='hs-keyglyph'>\</span> <span class='hs-varid'>env</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>tryIOEnvFailure</span> <span class='hs-layout'>(</span><span class='hs-varid'>thing</span> <span class='hs-varid'>env</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span>
<a name="line-119"></a>
<a name="line-120"></a><a name="tryIOEnvFailure"></a><span class='hs-definition'>tryIOEnvFailure</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>IO</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>IO</span> <span class='hs-layout'>(</span><span class='hs-conid'>Either</span> <span class='hs-conid'>IOEnvFailure</span> <span class='hs-varid'>a</span><span class='hs-layout'>)</span>
<a name="line-121"></a><span class='hs-definition'>tryIOEnvFailure</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>try</span>
<a name="line-122"></a>
<a name="line-123"></a><a name="tryAllM"></a><span class='hs-comment'>-- XXX We shouldn't be catching everything, e.g. timeouts</span>
<a name="line-124"></a><span class='hs-definition'>tryAllM</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>IOEnv</span> <span class='hs-varid'>env</span> <span class='hs-varid'>r</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>IOEnv</span> <span class='hs-varid'>env</span> <span class='hs-layout'>(</span><span class='hs-conid'>Either</span> <span class='hs-conid'>SomeException</span> <span class='hs-varid'>r</span><span class='hs-layout'>)</span>
<a name="line-125"></a><span class='hs-comment'>-- Catch *all* exceptions</span>
<a name="line-126"></a><span class='hs-comment'>-- This is used when running a Template-Haskell splice, when</span>
<a name="line-127"></a><span class='hs-comment'>-- even a pattern-match failure is a programmer error</span>
<a name="line-128"></a><span class='hs-definition'>tryAllM</span> <span class='hs-layout'>(</span><span class='hs-conid'>IOEnv</span> <span class='hs-varid'>thing</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>IOEnv</span> <span class='hs-layout'>(</span><span class='hs-keyglyph'>\</span> <span class='hs-varid'>env</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>try</span> <span class='hs-layout'>(</span><span class='hs-varid'>thing</span> <span class='hs-varid'>env</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span>
<a name="line-129"></a>
<a name="line-130"></a><a name="tryMostM"></a><span class='hs-definition'>tryMostM</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>IOEnv</span> <span class='hs-varid'>env</span> <span class='hs-varid'>r</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>IOEnv</span> <span class='hs-varid'>env</span> <span class='hs-layout'>(</span><span class='hs-conid'>Either</span> <span class='hs-conid'>SomeException</span> <span class='hs-varid'>r</span><span class='hs-layout'>)</span>
<a name="line-131"></a><span class='hs-definition'>tryMostM</span> <span class='hs-layout'>(</span><span class='hs-conid'>IOEnv</span> <span class='hs-varid'>thing</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>IOEnv</span> <span class='hs-layout'>(</span><span class='hs-keyglyph'>\</span> <span class='hs-varid'>env</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>tryMost</span> <span class='hs-layout'>(</span><span class='hs-varid'>thing</span> <span class='hs-varid'>env</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span>
<a name="line-132"></a>
<a name="line-133"></a><a name="unsafeInterleaveM"></a><span class='hs-comment'>---------------------------</span>
<a name="line-134"></a><span class='hs-definition'>unsafeInterleaveM</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>IOEnv</span> <span class='hs-varid'>env</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>IOEnv</span> <span class='hs-varid'>env</span> <span class='hs-varid'>a</span>
<a name="line-135"></a><span class='hs-definition'>unsafeInterleaveM</span> <span class='hs-layout'>(</span><span class='hs-conid'>IOEnv</span> <span class='hs-varid'>m</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>IOEnv</span> <span class='hs-layout'>(</span><span class='hs-keyglyph'>\</span> <span class='hs-varid'>env</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>unsafeInterleaveIO</span> <span class='hs-layout'>(</span><span class='hs-varid'>m</span> <span class='hs-varid'>env</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span>
<a name="line-136"></a>
<a name="line-137"></a>
<a name="line-138"></a><span class='hs-comment'>----------------------------------------------------------------------</span>
<a name="line-139"></a><span class='hs-comment'>-- MonadPlus</span>
<a name="line-140"></a><span class='hs-comment'>----------------------------------------------------------------------</span>
<a name="line-141"></a>
<a name="line-142"></a><span class='hs-comment'>-- For use if the user has imported Control.Monad.Error from MTL</span>
<a name="line-143"></a><span class='hs-comment'>-- Requires UndecidableInstances</span>
<a name="line-144"></a><span class='hs-keyword'>instance</span> <span class='hs-conid'>MonadPlus</span> <span class='hs-conid'>IO</span> <span class='hs-keyglyph'>=></span> <span class='hs-conid'>MonadPlus</span> <span class='hs-layout'>(</span><span class='hs-conid'>IOEnv</span> <span class='hs-varid'>env</span><span class='hs-layout'>)</span> <span class='hs-keyword'>where</span>
<a name="line-145"></a> <span class='hs-varid'>mzero</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>IOEnv</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-146"></a> <span class='hs-varid'>m</span> <span class='hs-varop'>`mplus`</span> <span class='hs-varid'>n</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>IOEnv</span> <span class='hs-layout'>(</span><span class='hs-keyglyph'>\</span><span class='hs-varid'>env</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>unIOEnv</span> <span class='hs-varid'>m</span> <span class='hs-varid'>env</span> <span class='hs-varop'>`mplus`</span> <span class='hs-varid'>unIOEnv</span> <span class='hs-varid'>n</span> <span class='hs-varid'>env</span><span class='hs-layout'>)</span>
<a name="line-147"></a>
<a name="line-148"></a><span class='hs-comment'>----------------------------------------------------------------------</span>
<a name="line-149"></a><span class='hs-comment'>-- Accessing input/output</span>
<a name="line-150"></a><span class='hs-comment'>----------------------------------------------------------------------</span>
<a name="line-151"></a>
<a name="line-152"></a><span class='hs-keyword'>instance</span> <span class='hs-conid'>MonadIO</span> <span class='hs-layout'>(</span><span class='hs-conid'>IOEnv</span> <span class='hs-varid'>env</span><span class='hs-layout'>)</span> <span class='hs-keyword'>where</span>
<a name="line-153"></a> <span class='hs-varid'>liftIO</span> <span class='hs-varid'>io</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>IOEnv</span> <span class='hs-layout'>(</span><span class='hs-keyglyph'>\</span> <span class='hs-keyword'>_</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>io</span><span class='hs-layout'>)</span>
<a name="line-154"></a>
<a name="line-155"></a><a name="newMutVar"></a><span class='hs-definition'>newMutVar</span> <span class='hs-keyglyph'>::</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>IOEnv</span> <span class='hs-varid'>env</span> <span class='hs-layout'>(</span><span class='hs-conid'>IORef</span> <span class='hs-varid'>a</span><span class='hs-layout'>)</span>
<a name="line-156"></a><span class='hs-definition'>newMutVar</span> <span class='hs-varid'>val</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>liftIO</span> <span class='hs-layout'>(</span><span class='hs-varid'>newIORef</span> <span class='hs-varid'>val</span><span class='hs-layout'>)</span>
<a name="line-157"></a>
<a name="line-158"></a><a name="writeMutVar"></a><span class='hs-definition'>writeMutVar</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>IORef</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>IOEnv</span> <span class='hs-varid'>env</span> <span class='hs-conid'>()</span>
<a name="line-159"></a><span class='hs-definition'>writeMutVar</span> <span class='hs-varid'>var</span> <span class='hs-varid'>val</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>liftIO</span> <span class='hs-layout'>(</span><span class='hs-varid'>writeIORef</span> <span class='hs-varid'>var</span> <span class='hs-varid'>val</span><span class='hs-layout'>)</span>
<a name="line-160"></a>
<a name="line-161"></a><a name="readMutVar"></a><span class='hs-definition'>readMutVar</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>IORef</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>IOEnv</span> <span class='hs-varid'>env</span> <span class='hs-varid'>a</span>
<a name="line-162"></a><span class='hs-definition'>readMutVar</span> <span class='hs-varid'>var</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>liftIO</span> <span class='hs-layout'>(</span><span class='hs-varid'>readIORef</span> <span class='hs-varid'>var</span><span class='hs-layout'>)</span>
<a name="line-163"></a>
<a name="line-164"></a><a name="updMutVar"></a><span class='hs-definition'>updMutVar</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>IORef</span> <span class='hs-varid'>a</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'>a</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>IOEnv</span> <span class='hs-varid'>env</span> <span class='hs-conid'>()</span>
<a name="line-165"></a><span class='hs-definition'>updMutVar</span> <span class='hs-varid'>var</span> <span class='hs-varid'>upd</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>liftIO</span> <span class='hs-layout'>(</span><span class='hs-varid'>modifyIORef</span> <span class='hs-varid'>var</span> <span class='hs-varid'>upd</span><span class='hs-layout'>)</span>
<a name="line-166"></a>
<a name="line-167"></a><a name="atomicUpdMutVar"></a><span class='hs-comment'>-- | Atomically update the reference. Does not force the evaluation of the</span>
<a name="line-168"></a><span class='hs-comment'>-- new variable contents. For strict update, use 'atomicUpdMutVar''.</span>
<a name="line-169"></a><span class='hs-definition'>atomicUpdMutVar</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>IORef</span> <span class='hs-varid'>a</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-layout'>(</span><span class='hs-varid'>a</span><span class='hs-layout'>,</span> <span class='hs-varid'>b</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>IOEnv</span> <span class='hs-varid'>env</span> <span class='hs-varid'>b</span>
<a name="line-170"></a><span class='hs-definition'>atomicUpdMutVar</span> <span class='hs-varid'>var</span> <span class='hs-varid'>upd</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>liftIO</span> <span class='hs-layout'>(</span><span class='hs-varid'>atomicModifyIORef</span> <span class='hs-varid'>var</span> <span class='hs-varid'>upd</span><span class='hs-layout'>)</span>
<a name="line-171"></a>
<a name="line-172"></a><a name="atomicUpdMutVar'"></a><span class='hs-comment'>-- | Strict variant of 'atomicUpdMutVar'.</span>
<a name="line-173"></a><span class='hs-definition'>atomicUpdMutVar'</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>IORef</span> <span class='hs-varid'>a</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-layout'>(</span><span class='hs-varid'>a</span><span class='hs-layout'>,</span> <span class='hs-varid'>b</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>IOEnv</span> <span class='hs-varid'>env</span> <span class='hs-varid'>b</span>
<a name="line-174"></a><span class='hs-definition'>atomicUpdMutVar'</span> <span class='hs-varid'>var</span> <span class='hs-varid'>upd</span> <span class='hs-keyglyph'>=</span> <span class='hs-keyword'>do</span>
<a name="line-175"></a> <span class='hs-varid'>r</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>atomicUpdMutVar</span> <span class='hs-varid'>var</span> <span class='hs-varid'>upd</span>
<a name="line-176"></a> <span class='hs-keyword'>_</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>liftIO</span> <span class='hs-varop'>.</span> <span class='hs-varid'>evaluate</span> <span class='hs-varop'>=<<</span> <span class='hs-varid'>readMutVar</span> <span class='hs-varid'>var</span>
<a name="line-177"></a> <span class='hs-varid'>return</span> <span class='hs-varid'>r</span>
<a name="line-178"></a>
<a name="line-179"></a><span class='hs-comment'>----------------------------------------------------------------------</span>
<a name="line-180"></a><span class='hs-comment'>-- Accessing the environment</span>
<a name="line-181"></a><span class='hs-comment'>----------------------------------------------------------------------</span>
<a name="line-182"></a>
<a name="line-183"></a><a name="getEnv"></a><span class='hs-definition'>getEnv</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>IOEnv</span> <span class='hs-varid'>env</span> <span class='hs-varid'>env</span>
<a name="line-184"></a><span class='hs-comment'>{-# INLINE getEnv #-}</span>
<a name="line-185"></a><span class='hs-definition'>getEnv</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>IOEnv</span> <span class='hs-layout'>(</span><span class='hs-keyglyph'>\</span> <span class='hs-varid'>env</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>return</span> <span class='hs-varid'>env</span><span class='hs-layout'>)</span>
<a name="line-186"></a>
<a name="line-187"></a><a name="setEnv"></a><span class='hs-comment'>-- | Perform a computation with a different environment</span>
<a name="line-188"></a><span class='hs-definition'>setEnv</span> <span class='hs-keyglyph'>::</span> <span class='hs-varid'>env'</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>IOEnv</span> <span class='hs-varid'>env'</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>IOEnv</span> <span class='hs-varid'>env</span> <span class='hs-varid'>a</span>
<a name="line-189"></a><span class='hs-comment'>{-# INLINE setEnv #-}</span>
<a name="line-190"></a><span class='hs-definition'>setEnv</span> <span class='hs-varid'>new_env</span> <span class='hs-layout'>(</span><span class='hs-conid'>IOEnv</span> <span class='hs-varid'>m</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>IOEnv</span> <span class='hs-layout'>(</span><span class='hs-keyglyph'>\</span> <span class='hs-keyword'>_</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>m</span> <span class='hs-varid'>new_env</span><span class='hs-layout'>)</span>
<a name="line-191"></a>
<a name="line-192"></a><a name="updEnv"></a><span class='hs-comment'>-- | Perform a computation with an altered environment</span>
<a name="line-193"></a><span class='hs-definition'>updEnv</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'>env'</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>IOEnv</span> <span class='hs-varid'>env'</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>IOEnv</span> <span class='hs-varid'>env</span> <span class='hs-varid'>a</span>
<a name="line-194"></a><span class='hs-comment'>{-# INLINE updEnv #-}</span>
<a name="line-195"></a><span class='hs-definition'>updEnv</span> <span class='hs-varid'>upd</span> <span class='hs-layout'>(</span><span class='hs-conid'>IOEnv</span> <span class='hs-varid'>m</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>IOEnv</span> <span class='hs-layout'>(</span><span class='hs-keyglyph'>\</span> <span class='hs-varid'>env</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>m</span> <span class='hs-layout'>(</span><span class='hs-varid'>upd</span> <span class='hs-varid'>env</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span>
<a name="line-196"></a>
<a name="line-197"></a>
<a name="line-198"></a><span class='hs-comment'>----------------------------------------------------------------------</span>
<a name="line-199"></a><span class='hs-comment'>-- Standard combinators, but specialised for this monad</span>
<a name="line-200"></a><span class='hs-comment'>-- (for efficiency)</span>
<a name="line-201"></a><span class='hs-comment'>----------------------------------------------------------------------</span>
<a name="line-202"></a>
<a name="line-203"></a><span class='hs-comment'>-- {-# SPECIALIZE mapM :: (a -> IOEnv env b) -> [a] -> IOEnv env [b] #-}</span>
<a name="line-204"></a><span class='hs-comment'>-- {-# SPECIALIZE mapM_ :: (a -> IOEnv env b) -> [a] -> IOEnv env () #-}</span>
<a name="line-205"></a><span class='hs-comment'>-- {-# SPECIALIZE mapSndM :: (b -> IOEnv env c) -> [(a,b)] -> IOEnv env [(a,c)] #-}</span>
<a name="line-206"></a><span class='hs-comment'>-- {-# SPECIALIZE sequence :: [IOEnv env a] -> IOEnv env [a] #-}</span>
<a name="line-207"></a><span class='hs-comment'>-- {-# SPECIALIZE sequence_ :: [IOEnv env a] -> IOEnv env () #-}</span>
<a name="line-208"></a><span class='hs-comment'>-- {-# SPECIALIZE foldlM :: (a -> b -> IOEnv env a) -> a -> [b] -> IOEnv env a #-}</span>
<a name="line-209"></a><span class='hs-comment'>-- {-# SPECIALIZE foldrM :: (b -> a -> IOEnv env a) -> a -> [b] -> IOEnv env a #-}</span>
<a name="line-210"></a><span class='hs-comment'>-- {-# SPECIALIZE mapAndUnzipM :: (a -> IOEnv env (b,c)) -> [a] -> IOEnv env ([b],[c]) #-}</span>
<a name="line-211"></a><span class='hs-comment'>-- {-# SPECIALIZE mapAndUnzip3M :: (a -> IOEnv env (b,c,d)) -> [a] -> IOEnv env ([b],[c],[d]) #-}</span>
<a name="line-212"></a><span class='hs-comment'>-- {-# SPECIALIZE zipWithM :: (a -> b -> IOEnv env c) -> [a] -> [b] -> IOEnv env [c] #-}</span>
<a name="line-213"></a><span class='hs-comment'>-- {-# SPECIALIZE zipWithM_ :: (a -> b -> IOEnv env c) -> [a] -> [b] -> IOEnv env () #-}</span>
<a name="line-214"></a><span class='hs-comment'>-- {-# SPECIALIZE anyM :: (a -> IOEnv env Bool) -> [a] -> IOEnv env Bool #-}</span>
<a name="line-215"></a><span class='hs-comment'>-- {-# SPECIALIZE when :: Bool -> IOEnv env a -> IOEnv env () #-}</span>
<a name="line-216"></a><span class='hs-comment'>-- {-# SPECIALIZE unless :: Bool -> IOEnv env a -> IOEnv env () #-}</span>
</pre></body>
</html>
