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<pre><a name="line-1"></a><span class='hs-comment'>{-# LANGUAGE BangPatterns, Rank2Types, ScopedTypeVariables, TypeOperators #-}</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.BloomFilter</span>
<a name="line-5"></a><span class='hs-comment'>-- Copyright: Bryan O'Sullivan</span>
<a name="line-6"></a><span class='hs-comment'>-- License: BSD3</span>
<a name="line-7"></a><span class='hs-comment'>--</span>
<a name="line-8"></a><span class='hs-comment'>-- Maintainer: Bryan O'Sullivan <bos@serpentine.com></span>
<a name="line-9"></a><span class='hs-comment'>-- Stability: unstable</span>
<a name="line-10"></a><span class='hs-comment'>-- Portability: portable</span>
<a name="line-11"></a><span class='hs-comment'>--</span>
<a name="line-12"></a><span class='hs-comment'>-- A fast, space efficient Bloom filter implementation. A Bloom</span>
<a name="line-13"></a><span class='hs-comment'>-- filter is a set-like data structure that provides a probabilistic</span>
<a name="line-14"></a><span class='hs-comment'>-- membership test.</span>
<a name="line-15"></a><span class='hs-comment'>--</span>
<a name="line-16"></a><span class='hs-comment'>-- * Queries do not give false negatives. When an element is added to</span>
<a name="line-17"></a><span class='hs-comment'>-- a filter, a subsequent membership test will definitely return</span>
<a name="line-18"></a><span class='hs-comment'>-- 'True'.</span>
<a name="line-19"></a><span class='hs-comment'>--</span>
<a name="line-20"></a><span class='hs-comment'>-- * False positives /are/ possible. If an element has not been added</span>
<a name="line-21"></a><span class='hs-comment'>-- to a filter, a membership test /may/ nevertheless indicate that</span>
<a name="line-22"></a><span class='hs-comment'>-- the element is present.</span>
<a name="line-23"></a><span class='hs-comment'>--</span>
<a name="line-24"></a><span class='hs-comment'>-- This module provides low-level control. For an easier to use</span>
<a name="line-25"></a><span class='hs-comment'>-- interface, see the "Data.BloomFilter.Easy" module.</span>
<a name="line-26"></a>
<a name="line-27"></a><span class='hs-keyword'>module</span> <span class='hs-conid'>Data</span><span class='hs-varop'>.</span><span class='hs-conid'>BloomFilter</span>
<a name="line-28"></a> <span class='hs-layout'>(</span>
<a name="line-29"></a> <span class='hs-comment'>-- * Overview</span>
<a name="line-30"></a> <span class='hs-comment'>-- $overview</span>
<a name="line-31"></a>
<a name="line-32"></a> <span class='hs-comment'>-- ** Ease of use</span>
<a name="line-33"></a> <span class='hs-comment'>-- $ease</span>
<a name="line-34"></a>
<a name="line-35"></a> <span class='hs-comment'>-- ** Performance</span>
<a name="line-36"></a> <span class='hs-comment'>-- $performance</span>
<a name="line-37"></a>
<a name="line-38"></a> <span class='hs-comment'>-- * Types</span>
<a name="line-39"></a> <span class='hs-conid'>Hash</span>
<a name="line-40"></a> <span class='hs-layout'>,</span> <span class='hs-conid'>Bloom</span>
<a name="line-41"></a> <span class='hs-layout'>,</span> <span class='hs-conid'>MBloom</span>
<a name="line-42"></a>
<a name="line-43"></a> <span class='hs-comment'>-- * Immutable Bloom filters</span>
<a name="line-44"></a>
<a name="line-45"></a> <span class='hs-comment'>-- ** Conversion</span>
<a name="line-46"></a> <span class='hs-layout'>,</span> <span class='hs-varid'>freeze</span>
<a name="line-47"></a> <span class='hs-layout'>,</span> <span class='hs-varid'>thaw</span>
<a name="line-48"></a> <span class='hs-layout'>,</span> <span class='hs-varid'>unsafeFreeze</span>
<a name="line-49"></a>
<a name="line-50"></a> <span class='hs-comment'>-- ** Creation</span>
<a name="line-51"></a> <span class='hs-layout'>,</span> <span class='hs-varid'>unfold</span>
<a name="line-52"></a>
<a name="line-53"></a> <span class='hs-layout'>,</span> <span class='hs-varid'>fromList</span>
<a name="line-54"></a> <span class='hs-layout'>,</span> <span class='hs-varid'>empty</span>
<a name="line-55"></a> <span class='hs-layout'>,</span> <span class='hs-varid'>singleton</span>
<a name="line-56"></a>
<a name="line-57"></a> <span class='hs-comment'>-- ** Accessors</span>
<a name="line-58"></a> <span class='hs-layout'>,</span> <span class='hs-varid'>length</span>
<a name="line-59"></a> <span class='hs-layout'>,</span> <span class='hs-varid'>elem</span>
<a name="line-60"></a> <span class='hs-layout'>,</span> <span class='hs-varid'>notElem</span>
<a name="line-61"></a>
<a name="line-62"></a> <span class='hs-comment'>-- ** Modification</span>
<a name="line-63"></a> <span class='hs-layout'>,</span> <span class='hs-varid'>insert</span>
<a name="line-64"></a> <span class='hs-layout'>,</span> <span class='hs-varid'>insertList</span>
<a name="line-65"></a>
<a name="line-66"></a> <span class='hs-comment'>-- * The underlying representation</span>
<a name="line-67"></a> <span class='hs-comment'>-- | If you serialize the raw bit arrays below to disk, do not</span>
<a name="line-68"></a> <span class='hs-comment'>-- expect them to be portable to systems with different</span>
<a name="line-69"></a> <span class='hs-comment'>-- conventions for endianness or word size.</span>
<a name="line-70"></a>
<a name="line-71"></a> <span class='hs-comment'>-- | The raw bit array used by the immutable 'Bloom' type.</span>
<a name="line-72"></a> <span class='hs-layout'>,</span> <span class='hs-varid'>bitArray</span>
<a name="line-73"></a> <span class='hs-layout'>)</span> <span class='hs-keyword'>where</span>
<a name="line-74"></a>
<a name="line-75"></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> <span class='hs-varid'>forM_</span><span class='hs-layout'>)</span>
<a name="line-76"></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'>ST</span> <span class='hs-layout'>(</span><span class='hs-conid'>ST</span><span class='hs-layout'>,</span> <span class='hs-varid'>runST</span><span class='hs-layout'>)</span>
<a name="line-77"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Control</span><span class='hs-varop'>.</span><span class='hs-conid'>DeepSeq</span> <span class='hs-layout'>(</span><span class='hs-conid'>NFData</span><span class='hs-layout'>(</span><span class='hs-keyglyph'>..</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span>
<a name="line-78"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Data</span><span class='hs-varop'>.</span><span class='hs-conid'>Array</span><span class='hs-varop'>.</span><span class='hs-conid'>Base</span> <span class='hs-layout'>(</span><span class='hs-varid'>unsafeAt</span><span class='hs-layout'>)</span>
<a name="line-79"></a><span class='hs-keyword'>import</span> <span class='hs-keyword'>qualified</span> <span class='hs-conid'>Data</span><span class='hs-varop'>.</span><span class='hs-conid'>Array</span><span class='hs-varop'>.</span><span class='hs-conid'>Base</span> <span class='hs-keyword'>as</span> <span class='hs-conid'>ST</span>
<a name="line-80"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Data</span><span class='hs-varop'>.</span><span class='hs-conid'>Array</span><span class='hs-varop'>.</span><span class='hs-conid'>Unboxed</span> <span class='hs-layout'>(</span><span class='hs-conid'>UArray</span><span class='hs-layout'>)</span>
<a name="line-81"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Data</span><span class='hs-varop'>.</span><span class='hs-conid'>Bits</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-82"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Data</span><span class='hs-varop'>.</span><span class='hs-conid'>BloomFilter</span><span class='hs-varop'>.</span><span class='hs-conid'>Util</span> <span class='hs-layout'>(</span><span class='hs-conid'>FastShift</span><span class='hs-layout'>(</span><span class='hs-keyglyph'>..</span><span class='hs-layout'>)</span><span class='hs-layout'>,</span> <span class='hs-layout'>(</span><span class='hs-conop'>:*</span><span class='hs-layout'>)</span><span class='hs-layout'>(</span><span class='hs-keyglyph'>..</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span>
<a name="line-83"></a><span class='hs-keyword'>import</span> <span class='hs-keyword'>qualified</span> <span class='hs-conid'>Data</span><span class='hs-varop'>.</span><span class='hs-conid'>BloomFilter</span><span class='hs-varop'>.</span><span class='hs-conid'>Mutable</span> <span class='hs-keyword'>as</span> <span class='hs-conid'>MB</span>
<a name="line-84"></a><span class='hs-keyword'>import</span> <span class='hs-keyword'>qualified</span> <span class='hs-conid'>Data</span><span class='hs-varop'>.</span><span class='hs-conid'>BloomFilter</span><span class='hs-varop'>.</span><span class='hs-conid'>Mutable</span><span class='hs-varop'>.</span><span class='hs-conid'>Internal</span> <span class='hs-keyword'>as</span> <span class='hs-conid'>MB</span>
<a name="line-85"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Data</span><span class='hs-varop'>.</span><span class='hs-conid'>BloomFilter</span><span class='hs-varop'>.</span><span class='hs-conid'>Mutable</span><span class='hs-varop'>.</span><span class='hs-conid'>Internal</span> <span class='hs-layout'>(</span><span class='hs-conid'>Hash</span><span class='hs-layout'>,</span> <span class='hs-conid'>MBloom</span><span class='hs-layout'>)</span>
<a name="line-86"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Data</span><span class='hs-varop'>.</span><span class='hs-conid'>Word</span> <span class='hs-layout'>(</span><span class='hs-conid'>Word32</span><span class='hs-layout'>)</span>
<a name="line-87"></a>
<a name="line-88"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Prelude</span> <span class='hs-varid'>hiding</span> <span class='hs-layout'>(</span><span class='hs-varid'>elem</span><span class='hs-layout'>,</span> <span class='hs-varid'>length</span><span class='hs-layout'>,</span> <span class='hs-varid'>notElem</span><span class='hs-layout'>,</span>
<a name="line-89"></a> <span class='hs-layout'>(</span><span class='hs-varop'>/</span><span class='hs-layout'>)</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> <span class='hs-varid'>div</span><span class='hs-layout'>,</span> <span class='hs-varid'>divMod</span><span class='hs-layout'>,</span> <span class='hs-varid'>mod</span><span class='hs-layout'>,</span> <span class='hs-varid'>rem</span><span class='hs-layout'>)</span>
<a name="line-90"></a>
<a name="line-91"></a>
<a name="line-92"></a><a name="Bloom"></a><span class='hs-comment'>-- | An immutable Bloom filter, suitable for querying from pure code.</span>
<a name="line-93"></a><a name="Bloom"></a><span class='hs-keyword'>data</span> <span class='hs-conid'>Bloom</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>B</span> <span class='hs-layout'>{</span>
<a name="line-94"></a> <span class='hs-varid'>hashes</span> <span class='hs-keyglyph'>::</span> <span class='hs-varop'>!</span><span class='hs-layout'>(</span><span class='hs-varid'>a</span> <span class='hs-keyglyph'>-></span> <span class='hs-keyglyph'>[</span><span class='hs-conid'>Hash</span><span class='hs-keyglyph'>]</span><span class='hs-layout'>)</span>
<a name="line-95"></a> <span class='hs-layout'>,</span> <span class='hs-varid'>shift</span> <span class='hs-keyglyph'>::</span> <span class='hs-comment'>{-# UNPACK #-}</span> <span class='hs-varop'>!</span><span class='hs-conid'>Int</span>
<a name="line-96"></a> <span class='hs-layout'>,</span> <span class='hs-varid'>mask</span> <span class='hs-keyglyph'>::</span> <span class='hs-comment'>{-# UNPACK #-}</span> <span class='hs-varop'>!</span><span class='hs-conid'>Int</span>
<a name="line-97"></a> <span class='hs-layout'>,</span> <span class='hs-varid'>bitArray</span> <span class='hs-keyglyph'>::</span> <span class='hs-comment'>{-# UNPACK #-}</span> <span class='hs-varop'>!</span><span class='hs-layout'>(</span><span class='hs-conid'>UArray</span> <span class='hs-conid'>Int</span> <span class='hs-conid'>Hash</span><span class='hs-layout'>)</span>
<a name="line-98"></a> <span class='hs-layout'>}</span>
<a name="line-99"></a>
<a name="line-100"></a><a name="instance%20Show%20(Bloom%20a)"></a><span class='hs-keyword'>instance</span> <span class='hs-conid'>Show</span> <span class='hs-layout'>(</span><span class='hs-conid'>Bloom</span> <span class='hs-varid'>a</span><span class='hs-layout'>)</span> <span class='hs-keyword'>where</span>
<a name="line-101"></a> <span class='hs-varid'>show</span> <span class='hs-varid'>ub</span> <span class='hs-keyglyph'>=</span> <span class='hs-str'>"Bloom { "</span> <span class='hs-varop'>++</span> <span class='hs-varid'>show</span> <span class='hs-layout'>(</span><span class='hs-layout'>(</span><span class='hs-num'>1</span><span class='hs-keyglyph'>::</span><span class='hs-conid'>Int</span><span class='hs-layout'>)</span> <span class='hs-varop'>`shiftL`</span> <span class='hs-varid'>shift</span> <span class='hs-varid'>ub</span><span class='hs-layout'>)</span> <span class='hs-varop'>++</span> <span class='hs-str'>" bits } "</span>
<a name="line-102"></a>
<a name="line-103"></a><a name="instance%20NFData%20(Bloom%20a)"></a><span class='hs-keyword'>instance</span> <span class='hs-conid'>NFData</span> <span class='hs-layout'>(</span><span class='hs-conid'>Bloom</span> <span class='hs-varid'>a</span><span class='hs-layout'>)</span> <span class='hs-keyword'>where</span>
<a name="line-104"></a> <span class='hs-varid'>rnf</span> <span class='hs-varop'>!</span><span class='hs-keyword'>_</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>()</span>
<a name="line-105"></a>
<a name="line-106"></a><a name="logBitsInHash"></a><span class='hs-definition'>logBitsInHash</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Int</span>
<a name="line-107"></a><span class='hs-definition'>logBitsInHash</span> <span class='hs-keyglyph'>=</span> <span class='hs-num'>5</span> <span class='hs-comment'>-- logPower2 bitsInHash</span>
<a name="line-108"></a>
<a name="line-109"></a><a name="create"></a><span class='hs-comment'>-- | Create an immutable Bloom filter, using the given setup function</span>
<a name="line-110"></a><span class='hs-comment'>-- which executes in the 'ST' monad.</span>
<a name="line-111"></a><span class='hs-comment'>--</span>
<a name="line-112"></a><span class='hs-comment'>-- Example:</span>
<a name="line-113"></a><span class='hs-comment'>--</span>
<a name="line-114"></a><span class='hs-comment'>-- @</span>
<a name="line-115"></a><span class='hs-comment'>--import "Data.BloomFilter.Hash" (cheapHashes)</span>
<a name="line-116"></a><span class='hs-comment'>--</span>
<a name="line-117"></a><span class='hs-comment'>--filter = create (cheapHashes 3) 1024 $ \mf -> do</span>
<a name="line-118"></a><span class='hs-comment'>-- insertMB mf \"foo\"</span>
<a name="line-119"></a><span class='hs-comment'>-- insertMB mf \"bar\"</span>
<a name="line-120"></a><span class='hs-comment'>-- @</span>
<a name="line-121"></a><span class='hs-comment'>--</span>
<a name="line-122"></a><span class='hs-comment'>-- Note that the result of the setup function is not used.</span>
<a name="line-123"></a><span class='hs-definition'>create</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-keyglyph'>[</span><span class='hs-conid'>Hash</span><span class='hs-keyglyph'>]</span><span class='hs-layout'>)</span> <span class='hs-comment'>-- ^ family of hash functions to use</span>
<a name="line-124"></a> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Int</span> <span class='hs-comment'>-- ^ number of bits in filter</span>
<a name="line-125"></a> <span class='hs-keyglyph'>-></span> <span class='hs-layout'>(</span><span class='hs-keyword'>forall</span> <span class='hs-varid'>s</span><span class='hs-varop'>.</span> <span class='hs-layout'>(</span><span class='hs-conid'>MBloom</span> <span class='hs-varid'>s</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>ST</span> <span class='hs-varid'>s</span> <span class='hs-conid'>()</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span> <span class='hs-comment'>-- ^ setup function</span>
<a name="line-126"></a> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Bloom</span> <span class='hs-varid'>a</span>
<a name="line-127"></a><span class='hs-comment'>{-# INLINE create #-}</span>
<a name="line-128"></a><span class='hs-definition'>create</span> <span class='hs-varid'>hash</span> <span class='hs-varid'>numBits</span> <span class='hs-varid'>body</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>runST</span> <span class='hs-varop'>$</span> <span class='hs-keyword'>do</span>
<a name="line-129"></a> <span class='hs-varid'>mb</span> <span class='hs-keyglyph'><-</span> <span class='hs-conid'>MB</span><span class='hs-varop'>.</span><span class='hs-varid'>new</span> <span class='hs-varid'>hash</span> <span class='hs-varid'>numBits</span>
<a name="line-130"></a> <span class='hs-varid'>body</span> <span class='hs-varid'>mb</span>
<a name="line-131"></a> <span class='hs-varid'>unsafeFreeze</span> <span class='hs-varid'>mb</span>
<a name="line-132"></a>
<a name="line-133"></a><a name="freeze"></a><span class='hs-comment'>-- | Create an immutable Bloom filter from a mutable one. The mutable</span>
<a name="line-134"></a><span class='hs-comment'>-- filter may be modified afterwards.</span>
<a name="line-135"></a><span class='hs-definition'>freeze</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>MBloom</span> <span class='hs-varid'>s</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>ST</span> <span class='hs-varid'>s</span> <span class='hs-layout'>(</span><span class='hs-conid'>Bloom</span> <span class='hs-varid'>a</span><span class='hs-layout'>)</span>
<a name="line-136"></a><span class='hs-definition'>freeze</span> <span class='hs-varid'>mb</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>B</span> <span class='hs-layout'>(</span><span class='hs-conid'>MB</span><span class='hs-varop'>.</span><span class='hs-varid'>hashes</span> <span class='hs-varid'>mb</span><span class='hs-layout'>)</span> <span class='hs-layout'>(</span><span class='hs-conid'>MB</span><span class='hs-varop'>.</span><span class='hs-varid'>shift</span> <span class='hs-varid'>mb</span><span class='hs-layout'>)</span> <span class='hs-layout'>(</span><span class='hs-conid'>MB</span><span class='hs-varop'>.</span><span class='hs-varid'>mask</span> <span class='hs-varid'>mb</span><span class='hs-layout'>)</span> <span class='hs-varop'>`liftM`</span>
<a name="line-137"></a> <span class='hs-conid'>ST</span><span class='hs-varop'>.</span><span class='hs-varid'>freeze</span> <span class='hs-layout'>(</span><span class='hs-conid'>MB</span><span class='hs-varop'>.</span><span class='hs-varid'>bitArray</span> <span class='hs-varid'>mb</span><span class='hs-layout'>)</span>
<a name="line-138"></a>
<a name="line-139"></a><a name="unsafeFreeze"></a><span class='hs-comment'>-- | Create an immutable Bloom filter from a mutable one. The mutable</span>
<a name="line-140"></a><span class='hs-comment'>-- filter /must not/ be modified afterwards, or a runtime crash may</span>
<a name="line-141"></a><span class='hs-comment'>-- occur. For a safer creation interface, use 'freeze' or 'create'.</span>
<a name="line-142"></a><span class='hs-definition'>unsafeFreeze</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>MBloom</span> <span class='hs-varid'>s</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>ST</span> <span class='hs-varid'>s</span> <span class='hs-layout'>(</span><span class='hs-conid'>Bloom</span> <span class='hs-varid'>a</span><span class='hs-layout'>)</span>
<a name="line-143"></a><span class='hs-definition'>unsafeFreeze</span> <span class='hs-varid'>mb</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>B</span> <span class='hs-layout'>(</span><span class='hs-conid'>MB</span><span class='hs-varop'>.</span><span class='hs-varid'>hashes</span> <span class='hs-varid'>mb</span><span class='hs-layout'>)</span> <span class='hs-layout'>(</span><span class='hs-conid'>MB</span><span class='hs-varop'>.</span><span class='hs-varid'>shift</span> <span class='hs-varid'>mb</span><span class='hs-layout'>)</span> <span class='hs-layout'>(</span><span class='hs-conid'>MB</span><span class='hs-varop'>.</span><span class='hs-varid'>mask</span> <span class='hs-varid'>mb</span><span class='hs-layout'>)</span> <span class='hs-varop'>`liftM`</span>
<a name="line-144"></a> <span class='hs-conid'>ST</span><span class='hs-varop'>.</span><span class='hs-varid'>unsafeFreeze</span> <span class='hs-layout'>(</span><span class='hs-conid'>MB</span><span class='hs-varop'>.</span><span class='hs-varid'>bitArray</span> <span class='hs-varid'>mb</span><span class='hs-layout'>)</span>
<a name="line-145"></a>
<a name="line-146"></a><a name="thaw"></a><span class='hs-comment'>-- | Copy an immutable Bloom filter to create a mutable one. There is</span>
<a name="line-147"></a><span class='hs-comment'>-- no non-copying equivalent.</span>
<a name="line-148"></a><span class='hs-definition'>thaw</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Bloom</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>ST</span> <span class='hs-varid'>s</span> <span class='hs-layout'>(</span><span class='hs-conid'>MBloom</span> <span class='hs-varid'>s</span> <span class='hs-varid'>a</span><span class='hs-layout'>)</span>
<a name="line-149"></a><span class='hs-definition'>thaw</span> <span class='hs-varid'>ub</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>MB</span><span class='hs-varop'>.</span><span class='hs-conid'>MB</span> <span class='hs-layout'>(</span><span class='hs-varid'>hashes</span> <span class='hs-varid'>ub</span><span class='hs-layout'>)</span> <span class='hs-layout'>(</span><span class='hs-varid'>shift</span> <span class='hs-varid'>ub</span><span class='hs-layout'>)</span> <span class='hs-layout'>(</span><span class='hs-varid'>mask</span> <span class='hs-varid'>ub</span><span class='hs-layout'>)</span> <span class='hs-varop'>`liftM`</span> <span class='hs-conid'>ST</span><span class='hs-varop'>.</span><span class='hs-varid'>thaw</span> <span class='hs-layout'>(</span><span class='hs-varid'>bitArray</span> <span class='hs-varid'>ub</span><span class='hs-layout'>)</span>
<a name="line-150"></a>
<a name="line-151"></a><a name="empty"></a><span class='hs-comment'>-- | Create an empty Bloom filter.</span>
<a name="line-152"></a><span class='hs-comment'>--</span>
<a name="line-153"></a><span class='hs-comment'>-- This function is subject to fusion with 'insert'</span>
<a name="line-154"></a><span class='hs-comment'>-- and 'insertList'.</span>
<a name="line-155"></a><span class='hs-definition'>empty</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-keyglyph'>[</span><span class='hs-conid'>Hash</span><span class='hs-keyglyph'>]</span><span class='hs-layout'>)</span> <span class='hs-comment'>-- ^ family of hash functions to use</span>
<a name="line-156"></a> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Int</span> <span class='hs-comment'>-- ^ number of bits in filter</span>
<a name="line-157"></a> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Bloom</span> <span class='hs-varid'>a</span>
<a name="line-158"></a><span class='hs-comment'>{-# INLINE [1] empty #-}</span>
<a name="line-159"></a><span class='hs-definition'>empty</span> <span class='hs-varid'>hash</span> <span class='hs-varid'>numBits</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>create</span> <span class='hs-varid'>hash</span> <span class='hs-varid'>numBits</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-conid'>()</span><span class='hs-layout'>)</span>
<a name="line-160"></a>
<a name="line-161"></a><a name="singleton"></a><span class='hs-comment'>-- | Create a Bloom filter with a single element.</span>
<a name="line-162"></a><span class='hs-comment'>--</span>
<a name="line-163"></a><span class='hs-comment'>-- This function is subject to fusion with 'insert'</span>
<a name="line-164"></a><span class='hs-comment'>-- and 'insertList'.</span>
<a name="line-165"></a><span class='hs-definition'>singleton</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-keyglyph'>[</span><span class='hs-conid'>Hash</span><span class='hs-keyglyph'>]</span><span class='hs-layout'>)</span> <span class='hs-comment'>-- ^ family of hash functions to use</span>
<a name="line-166"></a> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Int</span> <span class='hs-comment'>-- ^ number of bits in filter</span>
<a name="line-167"></a> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>a</span> <span class='hs-comment'>-- ^ element to insert</span>
<a name="line-168"></a> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Bloom</span> <span class='hs-varid'>a</span>
<a name="line-169"></a><span class='hs-comment'>{-# INLINE [1] singleton #-}</span>
<a name="line-170"></a><span class='hs-definition'>singleton</span> <span class='hs-varid'>hash</span> <span class='hs-varid'>numBits</span> <span class='hs-varid'>elt</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>create</span> <span class='hs-varid'>hash</span> <span class='hs-varid'>numBits</span> <span class='hs-layout'>(</span><span class='hs-keyglyph'>\</span><span class='hs-varid'>mb</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>MB</span><span class='hs-varop'>.</span><span class='hs-varid'>insert</span> <span class='hs-varid'>mb</span> <span class='hs-varid'>elt</span><span class='hs-layout'>)</span>
<a name="line-171"></a>
<a name="line-172"></a><a name="hashIdx"></a><span class='hs-comment'>-- | Given a filter's mask and a hash value, compute an offset into</span>
<a name="line-173"></a><span class='hs-comment'>-- a word array and a bit offset within that word.</span>
<a name="line-174"></a><span class='hs-definition'>hashIdx</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Int</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Word32</span> <span class='hs-keyglyph'>-></span> <span class='hs-layout'>(</span><span class='hs-conid'>Int</span> <span class='hs-conop'>:*</span> <span class='hs-conid'>Int</span><span class='hs-layout'>)</span>
<a name="line-175"></a><span class='hs-definition'>hashIdx</span> <span class='hs-varid'>mask</span> <span class='hs-varid'>x</span> <span class='hs-keyglyph'>=</span> <span class='hs-layout'>(</span><span class='hs-varid'>y</span> <span class='hs-varop'>`shiftR`</span> <span class='hs-varid'>logBitsInHash</span><span class='hs-layout'>)</span> <span class='hs-conop'>:*</span> <span class='hs-layout'>(</span><span class='hs-varid'>y</span> <span class='hs-varop'>.&.</span> <span class='hs-varid'>hashMask</span><span class='hs-layout'>)</span>
<a name="line-176"></a> <span class='hs-keyword'>where</span> <span class='hs-varid'>hashMask</span> <span class='hs-keyglyph'>=</span> <span class='hs-num'>31</span> <span class='hs-comment'>-- bitsInHash - 1</span>
<a name="line-177"></a> <span class='hs-varid'>y</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>fromIntegral</span> <span class='hs-varid'>x</span> <span class='hs-varop'>.&.</span> <span class='hs-varid'>mask</span>
<a name="line-178"></a>
<a name="line-179"></a><a name="hashesM"></a><span class='hs-comment'>-- | Hash the given value, returning a list of (word offset, bit</span>
<a name="line-180"></a><span class='hs-comment'>-- offset) pairs, one per hash value.</span>
<a name="line-181"></a><span class='hs-definition'>hashesM</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>MBloom</span> <span class='hs-varid'>s</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-keyglyph'>[</span><span class='hs-conid'>Int</span> <span class='hs-conop'>:*</span> <span class='hs-conid'>Int</span><span class='hs-keyglyph'>]</span>
<a name="line-182"></a><span class='hs-definition'>hashesM</span> <span class='hs-varid'>mb</span> <span class='hs-varid'>elt</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>hashIdx</span> <span class='hs-layout'>(</span><span class='hs-conid'>MB</span><span class='hs-varop'>.</span><span class='hs-varid'>mask</span> <span class='hs-varid'>mb</span><span class='hs-layout'>)</span> <span class='hs-varop'>`map`</span> <span class='hs-conid'>MB</span><span class='hs-varop'>.</span><span class='hs-varid'>hashes</span> <span class='hs-varid'>mb</span> <span class='hs-varid'>elt</span>
<a name="line-183"></a>
<a name="line-184"></a><a name="hashesU"></a><span class='hs-comment'>-- | Hash the given value, returning a list of (word offset, bit</span>
<a name="line-185"></a><span class='hs-comment'>-- offset) pairs, one per hash value.</span>
<a name="line-186"></a><span class='hs-definition'>hashesU</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Bloom</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-keyglyph'>[</span><span class='hs-conid'>Int</span> <span class='hs-conop'>:*</span> <span class='hs-conid'>Int</span><span class='hs-keyglyph'>]</span>
<a name="line-187"></a><span class='hs-definition'>hashesU</span> <span class='hs-varid'>ub</span> <span class='hs-varid'>elt</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>hashIdx</span> <span class='hs-layout'>(</span><span class='hs-varid'>mask</span> <span class='hs-varid'>ub</span><span class='hs-layout'>)</span> <span class='hs-varop'>`map`</span> <span class='hs-varid'>hashes</span> <span class='hs-varid'>ub</span> <span class='hs-varid'>elt</span>
<a name="line-188"></a>
<a name="line-189"></a><a name="elem"></a><span class='hs-comment'>-- | Query an immutable Bloom filter for membership. If the value is</span>
<a name="line-190"></a><span class='hs-comment'>-- present, return @True@. If the value is not present, there is</span>
<a name="line-191"></a><span class='hs-comment'>-- /still/ some possibility that @True@ will be returned.</span>
<a name="line-192"></a><span class='hs-definition'>elem</span> <span class='hs-keyglyph'>::</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Bloom</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Bool</span>
<a name="line-193"></a><span class='hs-definition'>elem</span> <span class='hs-varid'>elt</span> <span class='hs-varid'>ub</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>all</span> <span class='hs-varid'>test</span> <span class='hs-layout'>(</span><span class='hs-varid'>hashesU</span> <span class='hs-varid'>ub</span> <span class='hs-varid'>elt</span><span class='hs-layout'>)</span>
<a name="line-194"></a> <span class='hs-keyword'>where</span> <span class='hs-varid'>test</span> <span class='hs-layout'>(</span><span class='hs-varid'>off</span> <span class='hs-conop'>:*</span> <span class='hs-varid'>bit</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-layout'>(</span><span class='hs-varid'>bitArray</span> <span class='hs-varid'>ub</span> <span class='hs-varop'>`unsafeAt`</span> <span class='hs-varid'>off</span><span class='hs-layout'>)</span> <span class='hs-varop'>.&.</span> <span class='hs-layout'>(</span><span class='hs-num'>1</span> <span class='hs-varop'>`shiftL`</span> <span class='hs-varid'>bit</span><span class='hs-layout'>)</span> <span class='hs-varop'>/=</span> <span class='hs-num'>0</span>
<a name="line-195"></a>
<a name="line-196"></a><a name="modify"></a><span class='hs-definition'>modify</span> <span class='hs-keyglyph'>::</span> <span class='hs-layout'>(</span><span class='hs-keyword'>forall</span> <span class='hs-varid'>s</span><span class='hs-varop'>.</span> <span class='hs-layout'>(</span><span class='hs-conid'>MBloom</span> <span class='hs-varid'>s</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>ST</span> <span class='hs-varid'>s</span> <span class='hs-varid'>z</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span> <span class='hs-comment'>-- ^ mutation function (result is discarded)</span>
<a name="line-197"></a> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Bloom</span> <span class='hs-varid'>a</span>
<a name="line-198"></a> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Bloom</span> <span class='hs-varid'>a</span>
<a name="line-199"></a><span class='hs-comment'>{-# INLINE modify #-}</span>
<a name="line-200"></a><span class='hs-definition'>modify</span> <span class='hs-varid'>body</span> <span class='hs-varid'>ub</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>runST</span> <span class='hs-varop'>$</span> <span class='hs-keyword'>do</span>
<a name="line-201"></a> <span class='hs-varid'>mb</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>thaw</span> <span class='hs-varid'>ub</span>
<a name="line-202"></a> <span class='hs-keyword'>_</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>body</span> <span class='hs-varid'>mb</span>
<a name="line-203"></a> <span class='hs-varid'>unsafeFreeze</span> <span class='hs-varid'>mb</span>
<a name="line-204"></a>
<a name="line-205"></a><a name="insert"></a><span class='hs-comment'>-- | Create a new Bloom filter from an existing one, with the given</span>
<a name="line-206"></a><span class='hs-comment'>-- member added.</span>
<a name="line-207"></a><span class='hs-comment'>--</span>
<a name="line-208"></a><span class='hs-comment'>-- This function may be expensive, as it is likely to cause the</span>
<a name="line-209"></a><span class='hs-comment'>-- underlying bit array to be copied.</span>
<a name="line-210"></a><span class='hs-comment'>--</span>
<a name="line-211"></a><span class='hs-comment'>-- Repeated applications of this function with itself are subject to</span>
<a name="line-212"></a><span class='hs-comment'>-- fusion.</span>
<a name="line-213"></a><span class='hs-definition'>insert</span> <span class='hs-keyglyph'>::</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Bloom</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Bloom</span> <span class='hs-varid'>a</span>
<a name="line-214"></a><span class='hs-comment'>{-# NOINLINE insert #-}</span>
<a name="line-215"></a><span class='hs-definition'>insert</span> <span class='hs-varid'>elt</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>modify</span> <span class='hs-layout'>(</span><span class='hs-varid'>flip</span> <span class='hs-conid'>MB</span><span class='hs-varop'>.</span><span class='hs-varid'>insert</span> <span class='hs-varid'>elt</span><span class='hs-layout'>)</span>
<a name="line-216"></a>
<a name="line-217"></a><a name="insertList"></a><span class='hs-comment'>-- | Create a new Bloom filter from an existing one, with the given</span>
<a name="line-218"></a><span class='hs-comment'>-- members added.</span>
<a name="line-219"></a><span class='hs-comment'>--</span>
<a name="line-220"></a><span class='hs-comment'>-- This function may be expensive, as it is likely to cause the</span>
<a name="line-221"></a><span class='hs-comment'>-- underlying bit array to be copied.</span>
<a name="line-222"></a><span class='hs-comment'>--</span>
<a name="line-223"></a><span class='hs-comment'>-- Repeated applications of this function with itself are subject to</span>
<a name="line-224"></a><span class='hs-comment'>-- fusion.</span>
<a name="line-225"></a><span class='hs-definition'>insertList</span> <span class='hs-keyglyph'>::</span> <span class='hs-keyglyph'>[</span><span class='hs-varid'>a</span><span class='hs-keyglyph'>]</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Bloom</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Bloom</span> <span class='hs-varid'>a</span>
<a name="line-226"></a><span class='hs-comment'>{-# NOINLINE insertList #-}</span>
<a name="line-227"></a><span class='hs-definition'>insertList</span> <span class='hs-varid'>elts</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>modify</span> <span class='hs-varop'>$</span> <span class='hs-keyglyph'>\</span><span class='hs-varid'>mb</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>mapM_</span> <span class='hs-layout'>(</span><span class='hs-conid'>MB</span><span class='hs-varop'>.</span><span class='hs-varid'>insert</span> <span class='hs-varid'>mb</span><span class='hs-layout'>)</span> <span class='hs-varid'>elts</span>
<a name="line-228"></a>
<a name="line-229"></a><span class='hs-comment'>{-# RULES "Bloom insert . insert" forall a b u.
<a name="line-230"></a> insert b (insert a u) = insertList [a,b] u
<a name="line-231"></a> #-}</span>
<a name="line-232"></a>
<a name="line-233"></a><span class='hs-comment'>{-# RULES "Bloom insertList . insert" forall x xs u.
<a name="line-234"></a> insertList xs (insert x u) = insertList (x:xs) u
<a name="line-235"></a> #-}</span>
<a name="line-236"></a>
<a name="line-237"></a><span class='hs-comment'>{-# RULES "Bloom insert . insertList" forall x xs u.
<a name="line-238"></a> insert x (insertList xs u) = insertList (x:xs) u
<a name="line-239"></a> #-}</span>
<a name="line-240"></a>
<a name="line-241"></a><span class='hs-comment'>{-# RULES "Bloom insertList . insertList" forall xs ys u.
<a name="line-242"></a> insertList xs (insertList ys u) = insertList (xs++ys) u
<a name="line-243"></a> #-}</span>
<a name="line-244"></a>
<a name="line-245"></a><span class='hs-comment'>{-# RULES "Bloom insertList . empty" forall h n xs.
<a name="line-246"></a> insertList xs (empty h n) = fromList h n xs
<a name="line-247"></a> #-}</span>
<a name="line-248"></a>
<a name="line-249"></a><span class='hs-comment'>{-# RULES "Bloom insertList . singleton" forall h n x xs.
<a name="line-250"></a> insertList xs (singleton h n x) = fromList h n (x:xs)
<a name="line-251"></a> #-}</span>
<a name="line-252"></a>
<a name="line-253"></a><a name="notElem"></a><span class='hs-comment'>-- | Query an immutable Bloom filter for non-membership. If the value</span>
<a name="line-254"></a><span class='hs-comment'>-- /is/ present, return @False@. If the value is not present, there</span>
<a name="line-255"></a><span class='hs-comment'>-- is /still/ some possibility that @True@ will be returned.</span>
<a name="line-256"></a><span class='hs-definition'>notElem</span> <span class='hs-keyglyph'>::</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Bloom</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Bool</span>
<a name="line-257"></a><span class='hs-definition'>notElem</span> <span class='hs-varid'>elt</span> <span class='hs-varid'>ub</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>any</span> <span class='hs-varid'>test</span> <span class='hs-layout'>(</span><span class='hs-varid'>hashesU</span> <span class='hs-varid'>ub</span> <span class='hs-varid'>elt</span><span class='hs-layout'>)</span>
<a name="line-258"></a> <span class='hs-keyword'>where</span> <span class='hs-varid'>test</span> <span class='hs-layout'>(</span><span class='hs-varid'>off</span> <span class='hs-conop'>:*</span> <span class='hs-varid'>bit</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-layout'>(</span><span class='hs-varid'>bitArray</span> <span class='hs-varid'>ub</span> <span class='hs-varop'>`unsafeAt`</span> <span class='hs-varid'>off</span><span class='hs-layout'>)</span> <span class='hs-varop'>.&.</span> <span class='hs-layout'>(</span><span class='hs-num'>1</span> <span class='hs-varop'>`shiftL`</span> <span class='hs-varid'>bit</span><span class='hs-layout'>)</span> <span class='hs-varop'>==</span> <span class='hs-num'>0</span>
<a name="line-259"></a>
<a name="line-260"></a><a name="length"></a><span class='hs-comment'>-- | Return the size of an immutable Bloom filter, in bits.</span>
<a name="line-261"></a><span class='hs-definition'>length</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Bloom</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Int</span>
<a name="line-262"></a><span class='hs-definition'>length</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>shiftL</span> <span class='hs-num'>1</span> <span class='hs-varop'>.</span> <span class='hs-varid'>shift</span>
<a name="line-263"></a>
<a name="line-264"></a><a name="unfold"></a><span class='hs-comment'>-- | Build an immutable Bloom filter from a seed value. The seeding</span>
<a name="line-265"></a><span class='hs-comment'>-- function populates the filter as follows.</span>
<a name="line-266"></a><span class='hs-comment'>--</span>
<a name="line-267"></a><span class='hs-comment'>-- * If it returns 'Nothing', it is finished producing values to</span>
<a name="line-268"></a><span class='hs-comment'>-- insert into the filter.</span>
<a name="line-269"></a><span class='hs-comment'>--</span>
<a name="line-270"></a><span class='hs-comment'>-- * If it returns @'Just' (a,b)@, @a@ is added to the filter and</span>
<a name="line-271"></a><span class='hs-comment'>-- @b@ is used as a new seed.</span>
<a name="line-272"></a><span class='hs-definition'>unfold</span> <span class='hs-keyglyph'>::</span> <span class='hs-keyword'>forall</span> <span class='hs-varid'>a</span> <span class='hs-varid'>b</span><span class='hs-varop'>.</span> <span class='hs-layout'>(</span><span class='hs-varid'>a</span> <span class='hs-keyglyph'>-></span> <span class='hs-keyglyph'>[</span><span class='hs-conid'>Hash</span><span class='hs-keyglyph'>]</span><span class='hs-layout'>)</span> <span class='hs-comment'>-- ^ family of hash functions to use</span>
<a name="line-273"></a> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Int</span> <span class='hs-comment'>-- ^ number of bits in filter</span>
<a name="line-274"></a> <span class='hs-keyglyph'>-></span> <span class='hs-layout'>(</span><span class='hs-varid'>b</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Maybe</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-comment'>-- ^ seeding function</span>
<a name="line-275"></a> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>b</span> <span class='hs-comment'>-- ^ initial seed</span>
<a name="line-276"></a> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Bloom</span> <span class='hs-varid'>a</span>
<a name="line-277"></a><span class='hs-comment'>{-# INLINE unfold #-}</span>
<a name="line-278"></a><span class='hs-definition'>unfold</span> <span class='hs-varid'>hashes</span> <span class='hs-varid'>numBits</span> <span class='hs-varid'>f</span> <span class='hs-varid'>k</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>create</span> <span class='hs-varid'>hashes</span> <span class='hs-varid'>numBits</span> <span class='hs-layout'>(</span><span class='hs-varid'>loop</span> <span class='hs-varid'>k</span><span class='hs-layout'>)</span>
<a name="line-279"></a> <span class='hs-keyword'>where</span> <span class='hs-varid'>loop</span> <span class='hs-keyglyph'>::</span> <span class='hs-keyword'>forall</span> <span class='hs-varid'>s</span><span class='hs-varop'>.</span> <span class='hs-varid'>b</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>MBloom</span> <span class='hs-varid'>s</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>ST</span> <span class='hs-varid'>s</span> <span class='hs-conid'>()</span>
<a name="line-280"></a> <span class='hs-varid'>loop</span> <span class='hs-varid'>j</span> <span class='hs-varid'>mb</span> <span class='hs-keyglyph'>=</span> <span class='hs-keyword'>case</span> <span class='hs-varid'>f</span> <span class='hs-varid'>j</span> <span class='hs-keyword'>of</span>
<a name="line-281"></a> <span class='hs-conid'>Just</span> <span class='hs-layout'>(</span><span class='hs-varid'>a</span><span class='hs-layout'>,</span> <span class='hs-varid'>j'</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>MB</span><span class='hs-varop'>.</span><span class='hs-varid'>insert</span> <span class='hs-varid'>mb</span> <span class='hs-varid'>a</span> <span class='hs-varop'>>></span> <span class='hs-varid'>loop</span> <span class='hs-varid'>j'</span> <span class='hs-varid'>mb</span>
<a name="line-282"></a> <span class='hs-keyword'>_</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>return</span> <span class='hs-conid'>()</span>
<a name="line-283"></a>
<a name="line-284"></a><a name="fromList"></a><span class='hs-comment'>-- | Create an immutable Bloom filter, populating it from a list of</span>
<a name="line-285"></a><span class='hs-comment'>-- values.</span>
<a name="line-286"></a><span class='hs-comment'>--</span>
<a name="line-287"></a><span class='hs-comment'>-- Here is an example that uses the @cheapHashes@ function from the</span>
<a name="line-288"></a><span class='hs-comment'>-- "Data.BloomFilter.Hash" module to create a hash function that</span>
<a name="line-289"></a><span class='hs-comment'>-- returns three hashes.</span>
<a name="line-290"></a><span class='hs-comment'>--</span>
<a name="line-291"></a><span class='hs-comment'>-- @</span>
<a name="line-292"></a><span class='hs-comment'>--import "Data.BloomFilter.Hash" (cheapHashes)</span>
<a name="line-293"></a><span class='hs-comment'>--</span>
<a name="line-294"></a><span class='hs-comment'>--filt = fromList (cheapHashes 3) 1024 [\"foo\", \"bar\", \"quux\"]</span>
<a name="line-295"></a><span class='hs-comment'>-- @</span>
<a name="line-296"></a><span class='hs-definition'>fromList</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-keyglyph'>[</span><span class='hs-conid'>Hash</span><span class='hs-keyglyph'>]</span><span class='hs-layout'>)</span> <span class='hs-comment'>-- ^ family of hash functions to use</span>
<a name="line-297"></a> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Int</span> <span class='hs-comment'>-- ^ number of bits in filter</span>
<a name="line-298"></a> <span class='hs-keyglyph'>-></span> <span class='hs-keyglyph'>[</span><span class='hs-varid'>a</span><span class='hs-keyglyph'>]</span> <span class='hs-comment'>-- ^ values to populate with</span>
<a name="line-299"></a> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Bloom</span> <span class='hs-varid'>a</span>
<a name="line-300"></a><span class='hs-comment'>{-# INLINE [1] fromList #-}</span>
<a name="line-301"></a><span class='hs-definition'>fromList</span> <span class='hs-varid'>hashes</span> <span class='hs-varid'>numBits</span> <span class='hs-varid'>list</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>create</span> <span class='hs-varid'>hashes</span> <span class='hs-varid'>numBits</span> <span class='hs-varop'>$</span> <span class='hs-varid'>forM_</span> <span class='hs-varid'>list</span> <span class='hs-varop'>.</span> <span class='hs-conid'>MB</span><span class='hs-varop'>.</span><span class='hs-varid'>insert</span>
<a name="line-302"></a>
<a name="line-303"></a><span class='hs-comment'>{-# RULES "Bloom insertList . fromList" forall h n xs ys.
<a name="line-304"></a> insertList xs (fromList h n ys) = fromList h n (xs ++ ys)
<a name="line-305"></a> #-}</span>
<a name="line-306"></a>
<a name="line-307"></a><span class='hs-comment'>{-
<a name="line-308"></a>-- This is a simpler definition, but GHC doesn't inline the unfold
<a name="line-309"></a>-- sensibly.
<a name="line-310"></a>
<a name="line-311"></a>fromList hashes numBits = unfold hashes numBits convert
<a name="line-312"></a> where convert (x:xs) = Just (x, xs)
<a name="line-313"></a> convert _ = Nothing
<a name="line-314"></a>-}</span>
<a name="line-315"></a>
<a name="line-316"></a><a name="logPower2"></a><span class='hs-comment'>-- | Slow, crummy way of computing the integer log of an integer known</span>
<a name="line-317"></a><span class='hs-comment'>-- to be a power of two.</span>
<a name="line-318"></a><span class='hs-definition'>logPower2</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Int</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Int</span>
<a name="line-319"></a><span class='hs-definition'>logPower2</span> <span class='hs-varid'>k</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>go</span> <span class='hs-num'>0</span> <span class='hs-varid'>k</span>
<a name="line-320"></a> <span class='hs-keyword'>where</span> <span class='hs-varid'>go</span> <span class='hs-varid'>j</span> <span class='hs-num'>1</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>j</span>
<a name="line-321"></a> <span class='hs-varid'>go</span> <span class='hs-varid'>j</span> <span class='hs-varid'>n</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>go</span> <span class='hs-layout'>(</span><span class='hs-varid'>j</span><span class='hs-varop'>+</span><span class='hs-num'>1</span><span class='hs-layout'>)</span> <span class='hs-layout'>(</span><span class='hs-varid'>n</span> <span class='hs-varop'>`shiftR`</span> <span class='hs-num'>1</span><span class='hs-layout'>)</span>
<a name="line-322"></a>
<a name="line-323"></a><span class='hs-comment'>-- $overview</span>
<a name="line-324"></a><span class='hs-comment'>--</span>
<a name="line-325"></a><span class='hs-comment'>-- Each of the functions for creating Bloom filters accepts two parameters:</span>
<a name="line-326"></a><span class='hs-comment'>--</span>
<a name="line-327"></a><span class='hs-comment'>-- * The number of bits that should be used for the filter. Note that</span>
<a name="line-328"></a><span class='hs-comment'>-- a filter is fixed in size; it cannot be resized after creation.</span>
<a name="line-329"></a><span class='hs-comment'>--</span>
<a name="line-330"></a><span class='hs-comment'>-- * A function that accepts a value, and should return a fixed-size</span>
<a name="line-331"></a><span class='hs-comment'>-- list of hashes of that value. To keep the false positive rate</span>
<a name="line-332"></a><span class='hs-comment'>-- low, the hashes computes should, as far as possible, be</span>
<a name="line-333"></a><span class='hs-comment'>-- independent.</span>
<a name="line-334"></a><span class='hs-comment'>--</span>
<a name="line-335"></a><span class='hs-comment'>-- By choosing these parameters with care, it is possible to tune for</span>
<a name="line-336"></a><span class='hs-comment'>-- a particular false positive rate. The @suggestSizing@ function in</span>
<a name="line-337"></a><span class='hs-comment'>-- the "Data.BloomFilter.Easy" module calculates useful estimates for</span>
<a name="line-338"></a><span class='hs-comment'>-- these parameters.</span>
<a name="line-339"></a>
<a name="line-340"></a><span class='hs-comment'>-- $ease</span>
<a name="line-341"></a><span class='hs-comment'>--</span>
<a name="line-342"></a><span class='hs-comment'>-- This module provides immutable interfaces for working with a</span>
<a name="line-343"></a><span class='hs-comment'>-- query-only Bloom filter, and for converting to and from mutable</span>
<a name="line-344"></a><span class='hs-comment'>-- Bloom filters.</span>
<a name="line-345"></a><span class='hs-comment'>--</span>
<a name="line-346"></a><span class='hs-comment'>-- For a higher-level interface that is easy to use, see the</span>
<a name="line-347"></a><span class='hs-comment'>-- 'Data.BloomFilter.Easy' module.</span>
<a name="line-348"></a>
<a name="line-349"></a><span class='hs-comment'>-- $performance</span>
<a name="line-350"></a><span class='hs-comment'>--</span>
<a name="line-351"></a><span class='hs-comment'>-- The implementation has been carefully tuned for high performance</span>
<a name="line-352"></a><span class='hs-comment'>-- and low space consumption.</span>
<a name="line-353"></a><span class='hs-comment'>--</span>
<a name="line-354"></a><span class='hs-comment'>-- For efficiency, the number of bits requested when creating a Bloom</span>
<a name="line-355"></a><span class='hs-comment'>-- filter is rounded up to the nearest power of two. This lets the</span>
<a name="line-356"></a><span class='hs-comment'>-- implementation use bitwise operations internally, instead of much</span>
<a name="line-357"></a><span class='hs-comment'>-- more expensive multiplication, division, and modulus operations.</span>
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