<?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>Data/Text/Lazy/Read.hs</title>
<link type='text/css' rel='stylesheet' href='hscolour.css' />
</head>
<body>
<pre><a name="line-1"></a><span class='hs-comment'>{-# LANGUAGE OverloadedStrings #-}</span>
<a name="line-2"></a>
<a name="line-3"></a><span class='hs-comment'>-- |</span>
<a name="line-4"></a><span class='hs-comment'>-- Module : Data.Text.Lazy.Read</span>
<a name="line-5"></a><span class='hs-comment'>-- Copyright : (c) 2010 Bryan O'Sullivan</span>
<a name="line-6"></a><span class='hs-comment'>--</span>
<a name="line-7"></a><span class='hs-comment'>-- License : BSD-style</span>
<a name="line-8"></a><span class='hs-comment'>-- Maintainer : bos@serpentine.com, rtomharper@googlemail.com,</span>
<a name="line-9"></a><span class='hs-comment'>-- duncan@haskell.org</span>
<a name="line-10"></a><span class='hs-comment'>-- Stability : experimental</span>
<a name="line-11"></a><span class='hs-comment'>-- Portability : GHC</span>
<a name="line-12"></a><span class='hs-comment'>--</span>
<a name="line-13"></a><span class='hs-comment'>-- Functions used frequently when reading textual data.</span>
<a name="line-14"></a><span class='hs-keyword'>module</span> <span class='hs-conid'>Data</span><span class='hs-varop'>.</span><span class='hs-conid'>Text</span><span class='hs-varop'>.</span><span class='hs-conid'>Lazy</span><span class='hs-varop'>.</span><span class='hs-conid'>Read</span>
<a name="line-15"></a> <span class='hs-layout'>(</span>
<a name="line-16"></a> <span class='hs-conid'>Reader</span>
<a name="line-17"></a> <span class='hs-layout'>,</span> <span class='hs-varid'>decimal</span>
<a name="line-18"></a> <span class='hs-layout'>,</span> <span class='hs-varid'>hexadecimal</span>
<a name="line-19"></a> <span class='hs-layout'>,</span> <span class='hs-varid'>signed</span>
<a name="line-20"></a> <span class='hs-layout'>,</span> <span class='hs-varid'>rational</span>
<a name="line-21"></a> <span class='hs-layout'>,</span> <span class='hs-varid'>double</span>
<a name="line-22"></a> <span class='hs-layout'>)</span> <span class='hs-keyword'>where</span>
<a name="line-23"></a>
<a name="line-24"></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'>liftM</span><span class='hs-layout'>)</span>
<a name="line-25"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Data</span><span class='hs-varop'>.</span><span class='hs-conid'>Char</span> <span class='hs-layout'>(</span><span class='hs-varid'>isDigit</span><span class='hs-layout'>,</span> <span class='hs-varid'>isHexDigit</span><span class='hs-layout'>,</span> <span class='hs-varid'>ord</span><span class='hs-layout'>)</span>
<a name="line-26"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Data</span><span class='hs-varop'>.</span><span class='hs-conid'>Ratio</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-27"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Data</span><span class='hs-varop'>.</span><span class='hs-conid'>Text</span><span class='hs-varop'>.</span><span class='hs-conid'>Lazy</span> <span class='hs-keyword'>as</span> <span class='hs-conid'>T</span>
<a name="line-28"></a>
<a name="line-29"></a><a name="Reader"></a><span class='hs-comment'>-- | Read some text. If the read succeeds, return its value and the</span>
<a name="line-30"></a><a name="Reader"></a><span class='hs-comment'>-- remaining text, otherwise an error message.</span>
<a name="line-31"></a><a name="Reader"></a><span class='hs-keyword'>type</span> <span class='hs-conid'>Reader</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>Text</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Either</span> <span class='hs-conid'>String</span> <span class='hs-layout'>(</span><span class='hs-varid'>a</span><span class='hs-layout'>,</span><span class='hs-conid'>Text</span><span class='hs-layout'>)</span>
<a name="line-32"></a>
<a name="line-33"></a><a name="decimal"></a><span class='hs-comment'>-- | Read a decimal integer. The input must begin with at least one</span>
<a name="line-34"></a><span class='hs-comment'>-- decimal digit, and is consumed until a non-digit or end of string</span>
<a name="line-35"></a><span class='hs-comment'>-- is reached.</span>
<a name="line-36"></a><span class='hs-comment'>--</span>
<a name="line-37"></a><span class='hs-comment'>-- This function does not handle leading sign characters. If you need</span>
<a name="line-38"></a><span class='hs-comment'>-- to handle signed input, use @'signed' 'decimal'@.</span>
<a name="line-39"></a><span class='hs-comment'>--</span>
<a name="line-40"></a><span class='hs-comment'>-- /Note/: For fixed-width integer types, this function does not</span>
<a name="line-41"></a><span class='hs-comment'>-- attempt to detect overflow, so a sufficiently long input may give</span>
<a name="line-42"></a><span class='hs-comment'>-- incorrect results.</span>
<a name="line-43"></a><span class='hs-definition'>decimal</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Integral</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>=></span> <span class='hs-conid'>Reader</span> <span class='hs-varid'>a</span>
<a name="line-44"></a><span class='hs-comment'>{-# SPECIALIZE decimal :: Reader Int #-}</span>
<a name="line-45"></a><span class='hs-comment'>{-# SPECIALIZE decimal :: Reader Integer #-}</span>
<a name="line-46"></a><span class='hs-definition'>decimal</span> <span class='hs-varid'>txt</span>
<a name="line-47"></a> <span class='hs-keyglyph'>|</span> <span class='hs-conid'>T</span><span class='hs-varop'>.</span><span class='hs-varid'>null</span> <span class='hs-varid'>h</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>Left</span> <span class='hs-str'>"input does not start with a digit"</span>
<a name="line-48"></a> <span class='hs-keyglyph'>|</span> <span class='hs-varid'>otherwise</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>Right</span> <span class='hs-layout'>(</span><span class='hs-conid'>T</span><span class='hs-varop'>.</span><span class='hs-varid'>foldl'</span> <span class='hs-varid'>go</span> <span class='hs-num'>0</span> <span class='hs-varid'>h</span><span class='hs-layout'>,</span> <span class='hs-varid'>t</span><span class='hs-layout'>)</span>
<a name="line-49"></a> <span class='hs-keyword'>where</span> <span class='hs-layout'>(</span><span class='hs-varid'>h</span><span class='hs-layout'>,</span><span class='hs-varid'>t</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>T</span><span class='hs-varop'>.</span><span class='hs-varid'>spanBy</span> <span class='hs-varid'>isDigit</span> <span class='hs-varid'>txt</span>
<a name="line-50"></a> <span class='hs-varid'>go</span> <span class='hs-varid'>n</span> <span class='hs-varid'>d</span> <span class='hs-keyglyph'>=</span> <span class='hs-layout'>(</span><span class='hs-varid'>n</span> <span class='hs-varop'>*</span> <span class='hs-num'>10</span> <span class='hs-varop'>+</span> <span class='hs-varid'>fromIntegral</span> <span class='hs-layout'>(</span><span class='hs-varid'>digitToInt</span> <span class='hs-varid'>d</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span>
<a name="line-51"></a>
<a name="line-52"></a><a name="hexadecimal"></a><span class='hs-comment'>-- | Read a hexadecimal integer, consisting of an optional leading</span>
<a name="line-53"></a><span class='hs-comment'>-- @\"0x\"@ followed by at least one decimal digit. Input is consumed</span>
<a name="line-54"></a><span class='hs-comment'>-- until a non-hex-digit or end of string is reached. This function</span>
<a name="line-55"></a><span class='hs-comment'>-- is case insensitive.</span>
<a name="line-56"></a><span class='hs-comment'>--</span>
<a name="line-57"></a><span class='hs-comment'>-- This function does not handle leading sign characters. If you need</span>
<a name="line-58"></a><span class='hs-comment'>-- to handle signed input, use @'signed' 'hexadecimal'@.</span>
<a name="line-59"></a><span class='hs-comment'>--</span>
<a name="line-60"></a><span class='hs-comment'>-- /Note/: For fixed-width integer types, this function does not</span>
<a name="line-61"></a><span class='hs-comment'>-- attempt to detect overflow, so a sufficiently long input may give</span>
<a name="line-62"></a><span class='hs-comment'>-- incorrect results.</span>
<a name="line-63"></a><span class='hs-definition'>hexadecimal</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Integral</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>=></span> <span class='hs-conid'>Reader</span> <span class='hs-varid'>a</span>
<a name="line-64"></a><span class='hs-comment'>{-# SPECIALIZE hexadecimal :: Reader Int #-}</span>
<a name="line-65"></a><span class='hs-comment'>{-# SPECIALIZE hexadecimal :: Reader Integer #-}</span>
<a name="line-66"></a><span class='hs-definition'>hexadecimal</span> <span class='hs-varid'>txt</span>
<a name="line-67"></a> <span class='hs-keyglyph'>|</span> <span class='hs-varid'>h</span> <span class='hs-varop'>==</span> <span class='hs-str'>"0x"</span> <span class='hs-varop'>||</span> <span class='hs-varid'>h</span> <span class='hs-varop'>==</span> <span class='hs-str'>"0X"</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>hex</span> <span class='hs-varid'>t</span>
<a name="line-68"></a> <span class='hs-keyglyph'>|</span> <span class='hs-varid'>otherwise</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>hex</span> <span class='hs-varid'>txt</span>
<a name="line-69"></a> <span class='hs-keyword'>where</span> <span class='hs-layout'>(</span><span class='hs-varid'>h</span><span class='hs-layout'>,</span><span class='hs-varid'>t</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>T</span><span class='hs-varop'>.</span><span class='hs-varid'>splitAt</span> <span class='hs-num'>2</span> <span class='hs-varid'>txt</span>
<a name="line-70"></a>
<a name="line-71"></a><a name="hex"></a><span class='hs-definition'>hex</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Integral</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>=></span> <span class='hs-conid'>Reader</span> <span class='hs-varid'>a</span>
<a name="line-72"></a><span class='hs-comment'>{-# SPECIALIZE hex :: Reader Int #-}</span>
<a name="line-73"></a><span class='hs-comment'>{-# SPECIALIZE hex :: Reader Integer #-}</span>
<a name="line-74"></a><span class='hs-definition'>hex</span> <span class='hs-varid'>txt</span>
<a name="line-75"></a> <span class='hs-keyglyph'>|</span> <span class='hs-conid'>T</span><span class='hs-varop'>.</span><span class='hs-varid'>null</span> <span class='hs-varid'>h</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>Left</span> <span class='hs-str'>"input does not start with a hexadecimal digit"</span>
<a name="line-76"></a> <span class='hs-keyglyph'>|</span> <span class='hs-varid'>otherwise</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>Right</span> <span class='hs-layout'>(</span><span class='hs-conid'>T</span><span class='hs-varop'>.</span><span class='hs-varid'>foldl'</span> <span class='hs-varid'>go</span> <span class='hs-num'>0</span> <span class='hs-varid'>h</span><span class='hs-layout'>,</span> <span class='hs-varid'>t</span><span class='hs-layout'>)</span>
<a name="line-77"></a> <span class='hs-keyword'>where</span> <span class='hs-layout'>(</span><span class='hs-varid'>h</span><span class='hs-layout'>,</span><span class='hs-varid'>t</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>T</span><span class='hs-varop'>.</span><span class='hs-varid'>spanBy</span> <span class='hs-varid'>isHexDigit</span> <span class='hs-varid'>txt</span>
<a name="line-78"></a> <span class='hs-varid'>go</span> <span class='hs-varid'>n</span> <span class='hs-varid'>d</span> <span class='hs-keyglyph'>=</span> <span class='hs-layout'>(</span><span class='hs-varid'>n</span> <span class='hs-varop'>*</span> <span class='hs-num'>16</span> <span class='hs-varop'>+</span> <span class='hs-varid'>fromIntegral</span> <span class='hs-layout'>(</span><span class='hs-varid'>hexDigitToInt</span> <span class='hs-varid'>d</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span>
<a name="line-79"></a>
<a name="line-80"></a><a name="hexDigitToInt"></a><span class='hs-definition'>hexDigitToInt</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Char</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Int</span>
<a name="line-81"></a><span class='hs-definition'>hexDigitToInt</span> <span class='hs-varid'>c</span>
<a name="line-82"></a> <span class='hs-keyglyph'>|</span> <span class='hs-varid'>c</span> <span class='hs-varop'>>=</span> <span class='hs-chr'>'0'</span> <span class='hs-varop'>&&</span> <span class='hs-varid'>c</span> <span class='hs-varop'><=</span> <span class='hs-chr'>'9'</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>ord</span> <span class='hs-varid'>c</span> <span class='hs-comment'>-</span> <span class='hs-varid'>ord</span> <span class='hs-chr'>'0'</span>
<a name="line-83"></a> <span class='hs-keyglyph'>|</span> <span class='hs-varid'>c</span> <span class='hs-varop'>>=</span> <span class='hs-chr'>'a'</span> <span class='hs-varop'>&&</span> <span class='hs-varid'>c</span> <span class='hs-varop'><=</span> <span class='hs-chr'>'f'</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>ord</span> <span class='hs-varid'>c</span> <span class='hs-comment'>-</span> <span class='hs-layout'>(</span><span class='hs-varid'>ord</span> <span class='hs-chr'>'a'</span> <span class='hs-comment'>-</span> <span class='hs-num'>10</span><span class='hs-layout'>)</span>
<a name="line-84"></a> <span class='hs-keyglyph'>|</span> <span class='hs-varid'>otherwise</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>ord</span> <span class='hs-varid'>c</span> <span class='hs-comment'>-</span> <span class='hs-layout'>(</span><span class='hs-varid'>ord</span> <span class='hs-chr'>'A'</span> <span class='hs-comment'>-</span> <span class='hs-num'>10</span><span class='hs-layout'>)</span>
<a name="line-85"></a>
<a name="line-86"></a><a name="digitToInt"></a><span class='hs-definition'>digitToInt</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Char</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Int</span>
<a name="line-87"></a><span class='hs-definition'>digitToInt</span> <span class='hs-varid'>c</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>ord</span> <span class='hs-varid'>c</span> <span class='hs-comment'>-</span> <span class='hs-varid'>ord</span> <span class='hs-chr'>'0'</span>
<a name="line-88"></a>
<a name="line-89"></a><a name="signed"></a><span class='hs-comment'>-- | Read an optional leading sign character (@\'-\'@ or @\'+\'@) and</span>
<a name="line-90"></a><span class='hs-comment'>-- apply it to the result of applying the given reader.</span>
<a name="line-91"></a><span class='hs-definition'>signed</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Num</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>=></span> <span class='hs-conid'>Reader</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Reader</span> <span class='hs-varid'>a</span>
<a name="line-92"></a><span class='hs-comment'>{-# INLINE signed #-}</span>
<a name="line-93"></a><span class='hs-definition'>signed</span> <span class='hs-varid'>f</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>runP</span> <span class='hs-layout'>(</span><span class='hs-varid'>signa</span> <span class='hs-layout'>(</span><span class='hs-conid'>P</span> <span class='hs-varid'>f</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span>
<a name="line-94"></a>
<a name="line-95"></a><a name="rational"></a><span class='hs-comment'>-- | Read a rational number.</span>
<a name="line-96"></a><span class='hs-comment'>--</span>
<a name="line-97"></a><span class='hs-comment'>-- This function accepts an optional leading sign character, followed</span>
<a name="line-98"></a><span class='hs-comment'>-- by at least one decimal digit. The syntax similar to that accepted</span>
<a name="line-99"></a><span class='hs-comment'>-- by the 'read' function, with the exception that a trailing @\'.\'@</span>
<a name="line-100"></a><span class='hs-comment'>-- or @\'e\'@ /not/ followed by a number is not consumed.</span>
<a name="line-101"></a><span class='hs-comment'>--</span>
<a name="line-102"></a><span class='hs-comment'>-- Examples:</span>
<a name="line-103"></a><span class='hs-comment'>--</span>
<a name="line-104"></a><span class='hs-comment'>-- >rational "3" == Right (3.0, "")</span>
<a name="line-105"></a><span class='hs-comment'>-- >rational "3.1" == Right (3.1, "")</span>
<a name="line-106"></a><span class='hs-comment'>-- >rational "3e4" == Right (30000.0, "")</span>
<a name="line-107"></a><span class='hs-comment'>-- >rational "3.1e4" == Right (31000.0, "")</span>
<a name="line-108"></a><span class='hs-comment'>-- >rational ".3" == Left "input does not start with a digit"</span>
<a name="line-109"></a><span class='hs-comment'>-- >rational "e3" == Left "input does not start with a digit"</span>
<a name="line-110"></a><span class='hs-comment'>--</span>
<a name="line-111"></a><span class='hs-comment'>-- Examples of differences from 'read':</span>
<a name="line-112"></a><span class='hs-comment'>--</span>
<a name="line-113"></a><span class='hs-comment'>-- >rational "3.foo" == Right (3.0, ".foo")</span>
<a name="line-114"></a><span class='hs-comment'>-- >rational "3e" == Right (3.0, "e")</span>
<a name="line-115"></a><span class='hs-definition'>rational</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>RealFloat</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>=></span> <span class='hs-conid'>Reader</span> <span class='hs-varid'>a</span>
<a name="line-116"></a><span class='hs-comment'>{-# SPECIALIZE rational :: Reader Double #-}</span>
<a name="line-117"></a><span class='hs-definition'>rational</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>floaty</span> <span class='hs-varop'>$</span> <span class='hs-keyglyph'>\</span><span class='hs-varid'>real</span> <span class='hs-varid'>frac</span> <span class='hs-varid'>fracDenom</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>fromRational</span> <span class='hs-varop'>$</span>
<a name="line-118"></a> <span class='hs-varid'>real</span> <span class='hs-varop'>%</span> <span class='hs-num'>1</span> <span class='hs-varop'>+</span> <span class='hs-varid'>frac</span> <span class='hs-varop'>%</span> <span class='hs-varid'>fracDenom</span>
<a name="line-119"></a>
<a name="line-120"></a><a name="double"></a><span class='hs-comment'>-- | Read a rational number.</span>
<a name="line-121"></a><span class='hs-comment'>--</span>
<a name="line-122"></a><span class='hs-comment'>-- The syntax accepted by this function is the same as for 'rational'.</span>
<a name="line-123"></a><span class='hs-comment'>--</span>
<a name="line-124"></a><span class='hs-comment'>-- /Note/: This function is almost ten times faster than 'rational',</span>
<a name="line-125"></a><span class='hs-comment'>-- but is slightly less accurate.</span>
<a name="line-126"></a><span class='hs-comment'>--</span>
<a name="line-127"></a><span class='hs-comment'>-- The 'Double' type supports about 16 decimal places of accuracy.</span>
<a name="line-128"></a><span class='hs-comment'>-- For 94.2% of numbers, this function and 'rational' give identical</span>
<a name="line-129"></a><span class='hs-comment'>-- results, but for the remaining 5.8%, this function loses precision</span>
<a name="line-130"></a><span class='hs-comment'>-- around the 15th decimal place. For 0.001% of numbers, this</span>
<a name="line-131"></a><span class='hs-comment'>-- function will lose precision at the 13th or 14th decimal place.</span>
<a name="line-132"></a><span class='hs-definition'>double</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Reader</span> <span class='hs-conid'>Double</span>
<a name="line-133"></a><span class='hs-definition'>double</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>floaty</span> <span class='hs-varop'>$</span> <span class='hs-keyglyph'>\</span><span class='hs-varid'>real</span> <span class='hs-varid'>frac</span> <span class='hs-varid'>fracDenom</span> <span class='hs-keyglyph'>-></span>
<a name="line-134"></a> <span class='hs-varid'>fromIntegral</span> <span class='hs-varid'>real</span> <span class='hs-varop'>+</span>
<a name="line-135"></a> <span class='hs-varid'>fromIntegral</span> <span class='hs-varid'>frac</span> <span class='hs-varop'>/</span> <span class='hs-varid'>fromIntegral</span> <span class='hs-varid'>fracDenom</span>
<a name="line-136"></a>
<a name="line-137"></a><a name="signa"></a><span class='hs-definition'>signa</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Num</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>=></span> <span class='hs-conid'>Parser</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Parser</span> <span class='hs-varid'>a</span>
<a name="line-138"></a><span class='hs-comment'>{-# SPECIALIZE signa :: Parser Int -> Parser Int #-}</span>
<a name="line-139"></a><span class='hs-comment'>{-# SPECIALIZE signa :: Parser Integer -> Parser Integer #-}</span>
<a name="line-140"></a><span class='hs-definition'>signa</span> <span class='hs-varid'>p</span> <span class='hs-keyglyph'>=</span> <span class='hs-keyword'>do</span>
<a name="line-141"></a> <span class='hs-varid'>sign</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>perhaps</span> <span class='hs-chr'>'+'</span> <span class='hs-varop'>$</span> <span class='hs-varid'>char</span> <span class='hs-layout'>(</span><span class='hs-keyglyph'>\</span><span class='hs-varid'>c</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>c</span> <span class='hs-varop'>==</span> <span class='hs-chr'>'-'</span> <span class='hs-varop'>||</span> <span class='hs-varid'>c</span> <span class='hs-varop'>==</span> <span class='hs-chr'>'+'</span><span class='hs-layout'>)</span>
<a name="line-142"></a> <span class='hs-keyword'>if</span> <span class='hs-varid'>sign</span> <span class='hs-varop'>==</span> <span class='hs-chr'>'+'</span> <span class='hs-keyword'>then</span> <span class='hs-varid'>p</span> <span class='hs-keyword'>else</span> <span class='hs-varid'>negate</span> <span class='hs-varop'>`liftM`</span> <span class='hs-varid'>p</span>
<a name="line-143"></a>
<a name="line-144"></a><a name="Parser"></a><span class='hs-keyword'>newtype</span> <span class='hs-conid'>Parser</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>P</span> <span class='hs-layout'>{</span>
<a name="line-145"></a> <span class='hs-varid'>runP</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Reader</span> <span class='hs-varid'>a</span>
<a name="line-146"></a> <span class='hs-layout'>}</span>
<a name="line-147"></a>
<a name="line-148"></a><span class='hs-keyword'>instance</span> <span class='hs-conid'>Monad</span> <span class='hs-conid'>Parser</span> <span class='hs-keyword'>where</span>
<a name="line-149"></a> <span class='hs-varid'>return</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>P</span> <span class='hs-varop'>$</span> <span class='hs-keyglyph'>\</span><span class='hs-varid'>t</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Right</span> <span class='hs-layout'>(</span><span class='hs-varid'>a</span><span class='hs-layout'>,</span><span class='hs-varid'>t</span><span class='hs-layout'>)</span>
<a name="line-150"></a> <span class='hs-comment'>{-# INLINE return #-}</span>
<a name="line-151"></a> <span class='hs-varid'>m</span> <span class='hs-varop'>>>=</span> <span class='hs-varid'>k</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>P</span> <span class='hs-varop'>$</span> <span class='hs-keyglyph'>\</span><span class='hs-varid'>t</span> <span class='hs-keyglyph'>-></span> <span class='hs-keyword'>case</span> <span class='hs-varid'>runP</span> <span class='hs-varid'>m</span> <span class='hs-varid'>t</span> <span class='hs-keyword'>of</span>
<a name="line-152"></a> <span class='hs-conid'>Left</span> <span class='hs-varid'>err</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Left</span> <span class='hs-varid'>err</span>
<a name="line-153"></a> <span class='hs-conid'>Right</span> <span class='hs-layout'>(</span><span class='hs-varid'>a</span><span class='hs-layout'>,</span><span class='hs-varid'>t'</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>runP</span> <span class='hs-layout'>(</span><span class='hs-varid'>k</span> <span class='hs-varid'>a</span><span class='hs-layout'>)</span> <span class='hs-varid'>t'</span>
<a name="line-154"></a> <span class='hs-comment'>{-# INLINE (>>=) #-}</span>
<a name="line-155"></a> <span class='hs-varid'>fail</span> <span class='hs-varid'>msg</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>P</span> <span class='hs-varop'>$</span> <span class='hs-keyglyph'>\</span><span class='hs-keyword'>_</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Left</span> <span class='hs-varid'>msg</span>
<a name="line-156"></a>
<a name="line-157"></a><a name="perhaps"></a><span class='hs-definition'>perhaps</span> <span class='hs-keyglyph'>::</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Parser</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Parser</span> <span class='hs-varid'>a</span>
<a name="line-158"></a><span class='hs-definition'>perhaps</span> <span class='hs-varid'>def</span> <span class='hs-varid'>m</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>P</span> <span class='hs-varop'>$</span> <span class='hs-keyglyph'>\</span><span class='hs-varid'>t</span> <span class='hs-keyglyph'>-></span> <span class='hs-keyword'>case</span> <span class='hs-varid'>runP</span> <span class='hs-varid'>m</span> <span class='hs-varid'>t</span> <span class='hs-keyword'>of</span>
<a name="line-159"></a> <span class='hs-conid'>Left</span> <span class='hs-keyword'>_</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Right</span> <span class='hs-layout'>(</span><span class='hs-varid'>def</span><span class='hs-layout'>,</span><span class='hs-varid'>t</span><span class='hs-layout'>)</span>
<a name="line-160"></a> <span class='hs-varid'>r</span><span class='hs-keyglyph'>@</span><span class='hs-layout'>(</span><span class='hs-conid'>Right</span> <span class='hs-keyword'>_</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>r</span>
<a name="line-161"></a>
<a name="line-162"></a><a name="char"></a><span class='hs-definition'>char</span> <span class='hs-keyglyph'>::</span> <span class='hs-layout'>(</span><span class='hs-conid'>Char</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Bool</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Parser</span> <span class='hs-conid'>Char</span>
<a name="line-163"></a><span class='hs-definition'>char</span> <span class='hs-varid'>p</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>P</span> <span class='hs-varop'>$</span> <span class='hs-keyglyph'>\</span><span class='hs-varid'>t</span> <span class='hs-keyglyph'>-></span> <span class='hs-keyword'>case</span> <span class='hs-conid'>T</span><span class='hs-varop'>.</span><span class='hs-varid'>uncons</span> <span class='hs-varid'>t</span> <span class='hs-keyword'>of</span>
<a name="line-164"></a> <span class='hs-conid'>Just</span> <span class='hs-layout'>(</span><span class='hs-varid'>c</span><span class='hs-layout'>,</span><span class='hs-varid'>t'</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>|</span> <span class='hs-varid'>p</span> <span class='hs-varid'>c</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Right</span> <span class='hs-layout'>(</span><span class='hs-varid'>c</span><span class='hs-layout'>,</span><span class='hs-varid'>t'</span><span class='hs-layout'>)</span>
<a name="line-165"></a> <span class='hs-keyword'>_</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Left</span> <span class='hs-str'>"character does not match"</span>
<a name="line-166"></a>
<a name="line-167"></a><a name="T"></a><span class='hs-keyword'>data</span> <span class='hs-conid'>T</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>T</span> <span class='hs-varop'>!</span><span class='hs-conid'>Integer</span> <span class='hs-varop'>!</span><span class='hs-conid'>Int</span>
<a name="line-168"></a>
<a name="line-169"></a><a name="floaty"></a><span class='hs-definition'>floaty</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>RealFloat</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>=></span> <span class='hs-layout'>(</span><span class='hs-conid'>Integer</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Integer</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Integer</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'>Reader</span> <span class='hs-varid'>a</span>
<a name="line-170"></a><span class='hs-comment'>{-# INLINE floaty #-}</span>
<a name="line-171"></a><span class='hs-definition'>floaty</span> <span class='hs-varid'>f</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>runP</span> <span class='hs-varop'>$</span> <span class='hs-keyword'>do</span>
<a name="line-172"></a> <span class='hs-varid'>sign</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>perhaps</span> <span class='hs-chr'>'+'</span> <span class='hs-varop'>$</span> <span class='hs-varid'>char</span> <span class='hs-layout'>(</span><span class='hs-keyglyph'>\</span><span class='hs-varid'>c</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>c</span> <span class='hs-varop'>==</span> <span class='hs-chr'>'-'</span> <span class='hs-varop'>||</span> <span class='hs-varid'>c</span> <span class='hs-varop'>==</span> <span class='hs-chr'>'+'</span><span class='hs-layout'>)</span>
<a name="line-173"></a> <span class='hs-varid'>real</span> <span class='hs-keyglyph'><-</span> <span class='hs-conid'>P</span> <span class='hs-varid'>decimal</span>
<a name="line-174"></a> <span class='hs-conid'>T</span> <span class='hs-varid'>fraction</span> <span class='hs-varid'>fracDigits</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>perhaps</span> <span class='hs-layout'>(</span><span class='hs-conid'>T</span> <span class='hs-num'>0</span> <span class='hs-num'>0</span><span class='hs-layout'>)</span> <span class='hs-varop'>$</span> <span class='hs-keyword'>do</span>
<a name="line-175"></a> <span class='hs-keyword'>_</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>char</span> <span class='hs-layout'>(</span><span class='hs-varop'>==</span><span class='hs-chr'>'.'</span><span class='hs-layout'>)</span>
<a name="line-176"></a> <span class='hs-varid'>digits</span> <span class='hs-keyglyph'><-</span> <span class='hs-conid'>P</span> <span class='hs-varop'>$</span> <span class='hs-keyglyph'>\</span><span class='hs-varid'>t</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Right</span> <span class='hs-layout'>(</span><span class='hs-varid'>fromIntegral</span> <span class='hs-varop'>.</span> <span class='hs-conid'>T</span><span class='hs-varop'>.</span><span class='hs-varid'>length</span> <span class='hs-varop'>$</span> <span class='hs-conid'>T</span><span class='hs-varop'>.</span><span class='hs-varid'>takeWhile</span> <span class='hs-varid'>isDigit</span> <span class='hs-varid'>t</span><span class='hs-layout'>,</span> <span class='hs-varid'>t</span><span class='hs-layout'>)</span>
<a name="line-177"></a> <span class='hs-varid'>n</span> <span class='hs-keyglyph'><-</span> <span class='hs-conid'>P</span> <span class='hs-varid'>decimal</span>
<a name="line-178"></a> <span class='hs-varid'>return</span> <span class='hs-varop'>$</span> <span class='hs-conid'>T</span> <span class='hs-varid'>n</span> <span class='hs-varid'>digits</span>
<a name="line-179"></a> <span class='hs-keyword'>let</span> <span class='hs-varid'>e</span> <span class='hs-varid'>c</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>c</span> <span class='hs-varop'>==</span> <span class='hs-chr'>'e'</span> <span class='hs-varop'>||</span> <span class='hs-varid'>c</span> <span class='hs-varop'>==</span> <span class='hs-chr'>'E'</span>
<a name="line-180"></a> <span class='hs-varid'>power</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>perhaps</span> <span class='hs-num'>0</span> <span class='hs-layout'>(</span><span class='hs-varid'>char</span> <span class='hs-varid'>e</span> <span class='hs-varop'>>></span> <span class='hs-varid'>signa</span> <span class='hs-layout'>(</span><span class='hs-conid'>P</span> <span class='hs-varid'>decimal</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Parser</span> <span class='hs-conid'>Int</span><span class='hs-layout'>)</span>
<a name="line-181"></a> <span class='hs-keyword'>let</span> <span class='hs-varid'>n</span> <span class='hs-keyglyph'>=</span> <span class='hs-keyword'>if</span> <span class='hs-varid'>fracDigits</span> <span class='hs-varop'>==</span> <span class='hs-num'>0</span>
<a name="line-182"></a> <span class='hs-keyword'>then</span> <span class='hs-keyword'>if</span> <span class='hs-varid'>power</span> <span class='hs-varop'>==</span> <span class='hs-num'>0</span>
<a name="line-183"></a> <span class='hs-keyword'>then</span> <span class='hs-varid'>fromIntegral</span> <span class='hs-varid'>real</span>
<a name="line-184"></a> <span class='hs-keyword'>else</span> <span class='hs-varid'>fromIntegral</span> <span class='hs-varid'>real</span> <span class='hs-varop'>*</span> <span class='hs-layout'>(</span><span class='hs-num'>10</span> <span class='hs-varop'>^^</span> <span class='hs-varid'>power</span><span class='hs-layout'>)</span>
<a name="line-185"></a> <span class='hs-keyword'>else</span> <span class='hs-keyword'>if</span> <span class='hs-varid'>power</span> <span class='hs-varop'>==</span> <span class='hs-num'>0</span>
<a name="line-186"></a> <span class='hs-keyword'>then</span> <span class='hs-varid'>f</span> <span class='hs-varid'>real</span> <span class='hs-varid'>fraction</span> <span class='hs-layout'>(</span><span class='hs-num'>10</span> <span class='hs-varop'>^</span> <span class='hs-varid'>fracDigits</span><span class='hs-layout'>)</span>
<a name="line-187"></a> <span class='hs-keyword'>else</span> <span class='hs-varid'>f</span> <span class='hs-varid'>real</span> <span class='hs-varid'>fraction</span> <span class='hs-layout'>(</span><span class='hs-num'>10</span> <span class='hs-varop'>^</span> <span class='hs-varid'>fracDigits</span><span class='hs-layout'>)</span> <span class='hs-varop'>*</span> <span class='hs-layout'>(</span><span class='hs-num'>10</span> <span class='hs-varop'>^^</span> <span class='hs-varid'>power</span><span class='hs-layout'>)</span>
<a name="line-188"></a> <span class='hs-varid'>return</span> <span class='hs-varop'>$!</span> <span class='hs-keyword'>if</span> <span class='hs-varid'>sign</span> <span class='hs-varop'>==</span> <span class='hs-chr'>'+'</span>
<a name="line-189"></a> <span class='hs-keyword'>then</span> <span class='hs-varid'>n</span>
<a name="line-190"></a> <span class='hs-keyword'>else</span> <span class='hs-comment'>-</span><span class='hs-varid'>n</span>
</pre></body>
</html>
