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<title>src/Darcs/Patch/Permutations.hs</title>
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<pre><a name="line-1"></a><span class='hs-comment'>-- Copyright (C) 2002-2003 David Roundy</span>
<a name="line-2"></a><span class='hs-comment'>-- Copyright (C) 2009 Ganesh Sittampalam</span>
<a name="line-3"></a><span class='hs-comment'>--</span>
<a name="line-4"></a><span class='hs-comment'>-- This program is free software; you can redistribute it and/or modify</span>
<a name="line-5"></a><span class='hs-comment'>-- it under the terms of the GNU General Public License as published by</span>
<a name="line-6"></a><span class='hs-comment'>-- the Free Software Foundation; either version 2, or (at your option)</span>
<a name="line-7"></a><span class='hs-comment'>-- any later version.</span>
<a name="line-8"></a><span class='hs-comment'>--</span>
<a name="line-9"></a><span class='hs-comment'>-- This program is distributed in the hope that it will be useful,</span>
<a name="line-10"></a><span class='hs-comment'>-- but WITHOUT ANY WARRANTY; without even the implied warranty of</span>
<a name="line-11"></a><span class='hs-comment'>-- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the</span>
<a name="line-12"></a><span class='hs-comment'>-- GNU General Public License for more details.</span>
<a name="line-13"></a><span class='hs-comment'>--</span>
<a name="line-14"></a><span class='hs-comment'>-- You should have received a copy of the GNU General Public License</span>
<a name="line-15"></a><span class='hs-comment'>-- along with this program; see the file COPYING. If not, write to</span>
<a name="line-16"></a><span class='hs-comment'>-- the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,</span>
<a name="line-17"></a><span class='hs-comment'>-- Boston, MA 02110-1301, USA.</span>
<a name="line-18"></a>
<a name="line-19"></a><span class='hs-comment'>{-# OPTIONS_GHC -fno-warn-orphans #-}</span>
<a name="line-20"></a><span class='hs-comment'>{-# LANGUAGE CPP #-}</span>
<a name="line-21"></a>
<a name="line-22"></a><span class='hs-cpp'>#include "gadts.h"</span>
<a name="line-23"></a>
<a name="line-24"></a><span class='hs-keyword'>module</span> <span class='hs-conid'>Darcs</span><span class='hs-varop'>.</span><span class='hs-conid'>Patch</span><span class='hs-varop'>.</span><span class='hs-conid'>Permutations</span> <span class='hs-layout'>(</span> <span class='hs-varid'>removeFL</span><span class='hs-layout'>,</span> <span class='hs-varid'>removeRL</span><span class='hs-layout'>,</span> <span class='hs-varid'>removeCommon</span><span class='hs-layout'>,</span>
<a name="line-25"></a> <span class='hs-varid'>commuteWhatWeCanFL</span><span class='hs-layout'>,</span> <span class='hs-varid'>commuteWhatWeCanRL</span><span class='hs-layout'>,</span>
<a name="line-26"></a> <span class='hs-varid'>genCommuteWhatWeCanRL</span><span class='hs-layout'>,</span>
<a name="line-27"></a> <span class='hs-varid'>partitionFL</span><span class='hs-layout'>,</span> <span class='hs-varid'>partitionRL</span><span class='hs-layout'>,</span>
<a name="line-28"></a> <span class='hs-varid'>simpleHeadPermutationsFL</span><span class='hs-layout'>,</span> <span class='hs-varid'>headPermutationsRL</span><span class='hs-layout'>,</span>
<a name="line-29"></a> <span class='hs-varid'>headPermutationsFL</span><span class='hs-layout'>,</span>
<a name="line-30"></a> <span class='hs-varid'>removeSubsequenceFL</span><span class='hs-layout'>,</span> <span class='hs-varid'>removeSubsequenceRL</span><span class='hs-layout'>,</span>
<a name="line-31"></a> <span class='hs-varid'>partitionConflictingFL</span><span class='hs-layout'>,</span>
<a name="line-32"></a> <span class='hs-conid'>CommuteFn</span><span class='hs-layout'>,</span> <span class='hs-varid'>selfCommuter</span><span class='hs-layout'>,</span>
<a name="line-33"></a> <span class='hs-varid'>commuterIdFL</span><span class='hs-layout'>,</span> <span class='hs-varid'>commuterFLId</span><span class='hs-layout'>,</span>
<a name="line-34"></a> <span class='hs-varid'>commuterIdRL</span>
<a name="line-35"></a> <span class='hs-layout'>)</span> <span class='hs-keyword'>where</span>
<a name="line-36"></a>
<a name="line-37"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Data</span><span class='hs-varop'>.</span><span class='hs-conid'>Maybe</span> <span class='hs-layout'>(</span> <span class='hs-varid'>mapMaybe</span> <span class='hs-layout'>)</span>
<a name="line-38"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Darcs</span><span class='hs-varop'>.</span><span class='hs-conid'>Patch</span><span class='hs-varop'>.</span><span class='hs-conid'>Commute</span> <span class='hs-layout'>(</span> <span class='hs-conid'>Commute</span><span class='hs-layout'>,</span> <span class='hs-varid'>commute</span><span class='hs-layout'>,</span> <span class='hs-varid'>commuteFLorComplain</span><span class='hs-layout'>,</span> <span class='hs-varid'>commuteRL</span> <span class='hs-layout'>)</span>
<a name="line-39"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Darcs</span><span class='hs-varop'>.</span><span class='hs-conid'>Patch</span><span class='hs-varop'>.</span><span class='hs-conid'>Invert</span> <span class='hs-layout'>(</span> <span class='hs-conid'>Invert</span><span class='hs-layout'>(</span><span class='hs-keyglyph'>..</span><span class='hs-layout'>)</span><span class='hs-layout'>,</span> <span class='hs-varid'>invertFL</span><span class='hs-layout'>,</span> <span class='hs-varid'>invertRL</span> <span class='hs-layout'>)</span>
<a name="line-40"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Darcs</span><span class='hs-varop'>.</span><span class='hs-conid'>Witnesses</span><span class='hs-varop'>.</span><span class='hs-conid'>Eq</span> <span class='hs-layout'>(</span> <span class='hs-conid'>MyEq</span><span class='hs-layout'>(</span><span class='hs-keyglyph'>..</span><span class='hs-layout'>)</span><span class='hs-layout'>,</span> <span class='hs-conid'>EqCheck</span><span class='hs-layout'>(</span><span class='hs-keyglyph'>..</span><span class='hs-layout'>)</span> <span class='hs-layout'>)</span>
<a name="line-41"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Darcs</span><span class='hs-varop'>.</span><span class='hs-conid'>Witnesses</span><span class='hs-varop'>.</span><span class='hs-conid'>Ordered</span> <span class='hs-layout'>(</span> <span class='hs-conid'>FL</span><span class='hs-layout'>(</span><span class='hs-keyglyph'>..</span><span class='hs-layout'>)</span><span class='hs-layout'>,</span> <span class='hs-conid'>RL</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> <span class='hs-layout'>(</span><span class='hs-varop'>+<+</span><span class='hs-layout'>)</span>
<a name="line-42"></a> <span class='hs-layout'>,</span> <span class='hs-varid'>reverseFL</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-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> <span class='hs-varid'>lengthFL</span>
<a name="line-43"></a> <span class='hs-layout'>,</span> <span class='hs-varid'>lengthRL</span><span class='hs-layout'>,</span> <span class='hs-varid'>reverseRL</span> <span class='hs-layout'>)</span>
<a name="line-44"></a><span class='hs-cpp'>#include "impossible.h"</span>
<a name="line-45"></a>
<a name="line-46"></a><a name="partitionFL"></a><span class='hs-comment'>-- |split an 'FL' into "left" and "right" lists according to a predicate @p@, using commutation as necessary.</span>
<a name="line-47"></a><span class='hs-comment'>-- If a patch does satisfy the predicate but cannot be commuted past one that does not satisfy</span>
<a name="line-48"></a><span class='hs-comment'>-- the predicate, it goes in the "middle" list; to sum up, we have: @all p left@ and @all (not.p) right@, while</span>
<a name="line-49"></a><span class='hs-comment'>-- midddle is mixed.</span>
<a name="line-50"></a><span class='hs-definition'>partitionFL</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Commute</span> <span class='hs-varid'>p</span>
<a name="line-51"></a> <span class='hs-keyglyph'>=></span> <span class='hs-layout'>(</span><span class='hs-conid'>FORALL</span><span class='hs-layout'>(</span><span class='hs-varid'>u</span> <span class='hs-varid'>v</span><span class='hs-layout'>)</span> <span class='hs-varid'>p</span> <span class='hs-conid'>C</span><span class='hs-layout'>(</span><span class='hs-varid'>u</span> <span class='hs-varid'>v</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Bool</span><span class='hs-layout'>)</span> <span class='hs-comment'>-- ^predicate; if true we would like the patch in the "left" list</span>
<a name="line-52"></a> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>FL</span> <span class='hs-varid'>p</span> <span class='hs-conid'>C</span><span class='hs-layout'>(</span><span class='hs-varid'>x</span> <span class='hs-varid'>y</span><span class='hs-layout'>)</span> <span class='hs-comment'>-- ^input 'FL'</span>
<a name="line-53"></a> <span class='hs-keyglyph'>-></span> <span class='hs-layout'>(</span><span class='hs-layout'>(</span><span class='hs-conid'>FL</span> <span class='hs-varid'>p</span> <span class='hs-conop'>:></span> <span class='hs-conid'>FL</span> <span class='hs-varid'>p</span> <span class='hs-conop'>:></span> <span class='hs-conid'>FL</span> <span class='hs-varid'>p</span><span class='hs-layout'>)</span> <span class='hs-conid'>C</span><span class='hs-layout'>(</span><span class='hs-varid'>x</span> <span class='hs-varid'>y</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span> <span class='hs-comment'>-- ^"left", "middle" and "right"</span>
<a name="line-54"></a>
<a name="line-55"></a><a name="partitionFL'"></a><span class='hs-comment'>-- optimise by using an accumulating parameter to track all the "right" patches that we've found so far</span>
<a name="line-56"></a><span class='hs-definition'>partitionFL'</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Commute</span> <span class='hs-varid'>p</span>
<a name="line-57"></a> <span class='hs-keyglyph'>=></span> <span class='hs-layout'>(</span><span class='hs-conid'>FORALL</span><span class='hs-layout'>(</span><span class='hs-varid'>u</span> <span class='hs-varid'>v</span><span class='hs-layout'>)</span> <span class='hs-varid'>p</span> <span class='hs-conid'>C</span><span class='hs-layout'>(</span><span class='hs-varid'>u</span> <span class='hs-varid'>v</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Bool</span><span class='hs-layout'>)</span>
<a name="line-58"></a> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>RL</span> <span class='hs-varid'>p</span> <span class='hs-conid'>C</span><span class='hs-layout'>(</span><span class='hs-varid'>a</span> <span class='hs-varid'>b</span><span class='hs-layout'>)</span> <span class='hs-comment'>-- the "middle" patches found so far</span>
<a name="line-59"></a> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>RL</span> <span class='hs-varid'>p</span> <span class='hs-conid'>C</span><span class='hs-layout'>(</span><span class='hs-varid'>b</span> <span class='hs-varid'>c</span><span class='hs-layout'>)</span> <span class='hs-comment'>-- the "right" patches found so far</span>
<a name="line-60"></a> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>FL</span> <span class='hs-varid'>p</span> <span class='hs-conid'>C</span><span class='hs-layout'>(</span><span class='hs-varid'>c</span> <span class='hs-varid'>d</span><span class='hs-layout'>)</span>
<a name="line-61"></a> <span class='hs-keyglyph'>-></span> <span class='hs-layout'>(</span><span class='hs-layout'>(</span><span class='hs-conid'>FL</span> <span class='hs-varid'>p</span> <span class='hs-conop'>:></span> <span class='hs-conid'>FL</span> <span class='hs-varid'>p</span> <span class='hs-conop'>:></span> <span class='hs-conid'>FL</span> <span class='hs-varid'>p</span><span class='hs-layout'>)</span> <span class='hs-conid'>C</span><span class='hs-layout'>(</span><span class='hs-varid'>a</span> <span class='hs-varid'>d</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span>
<a name="line-62"></a>
<a name="line-63"></a><span class='hs-definition'>partitionFL</span> <span class='hs-varid'>keepleft</span> <span class='hs-varid'>ps</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>partitionFL'</span> <span class='hs-varid'>keepleft</span> <span class='hs-conid'>NilRL</span> <span class='hs-conid'>NilRL</span> <span class='hs-varid'>ps</span>
<a name="line-64"></a>
<a name="line-65"></a><span class='hs-definition'>partitionFL'</span> <span class='hs-keyword'>_</span> <span class='hs-varid'>middle</span> <span class='hs-varid'>right</span> <span class='hs-conid'>NilFL</span> <span class='hs-keyglyph'>=</span> <span class='hs-layout'>(</span><span class='hs-conid'>NilFL</span> <span class='hs-conop'>:></span> <span class='hs-varid'>reverseRL</span> <span class='hs-varid'>middle</span> <span class='hs-conop'>:></span> <span class='hs-varid'>reverseRL</span> <span class='hs-varid'>right</span><span class='hs-layout'>)</span>
<a name="line-66"></a><span class='hs-definition'>partitionFL'</span> <span class='hs-varid'>keepleft</span> <span class='hs-varid'>middle</span> <span class='hs-varid'>right</span> <span class='hs-layout'>(</span><span class='hs-varid'>p</span> <span class='hs-conop'>:>:</span> <span class='hs-varid'>ps</span><span class='hs-layout'>)</span>
<a name="line-67"></a> <span class='hs-keyglyph'>|</span> <span class='hs-varid'>keepleft</span> <span class='hs-varid'>p</span> <span class='hs-keyglyph'>=</span> <span class='hs-keyword'>case</span> <span class='hs-varid'>commuteRL</span> <span class='hs-layout'>(</span><span class='hs-varid'>right</span> <span class='hs-conop'>:></span> <span class='hs-varid'>p</span><span class='hs-layout'>)</span> <span class='hs-keyword'>of</span>
<a name="line-68"></a> <span class='hs-conid'>Just</span> <span class='hs-layout'>(</span><span class='hs-varid'>p'</span> <span class='hs-conop'>:></span> <span class='hs-varid'>right'</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>-></span> <span class='hs-keyword'>case</span> <span class='hs-varid'>commuteRL</span> <span class='hs-layout'>(</span><span class='hs-varid'>middle</span> <span class='hs-conop'>:></span> <span class='hs-varid'>p'</span><span class='hs-layout'>)</span> <span class='hs-keyword'>of</span>
<a name="line-69"></a> <span class='hs-conid'>Just</span> <span class='hs-layout'>(</span><span class='hs-varid'>p''</span> <span class='hs-conop'>:></span> <span class='hs-varid'>middle'</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>-></span> <span class='hs-keyword'>case</span> <span class='hs-varid'>partitionFL'</span> <span class='hs-varid'>keepleft</span> <span class='hs-varid'>middle'</span> <span class='hs-varid'>right'</span> <span class='hs-varid'>ps</span> <span class='hs-keyword'>of</span>
<a name="line-70"></a> <span class='hs-layout'>(</span><span class='hs-varid'>a</span> <span class='hs-conop'>:></span> <span class='hs-varid'>b</span> <span class='hs-conop'>:></span> <span class='hs-varid'>c</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>-></span> <span class='hs-layout'>(</span><span class='hs-varid'>p''</span> <span class='hs-conop'>:>:</span> <span class='hs-varid'>a</span> <span class='hs-conop'>:></span> <span class='hs-varid'>b</span> <span class='hs-conop'>:></span> <span class='hs-varid'>c</span><span class='hs-layout'>)</span>
<a name="line-71"></a> <span class='hs-conid'>Nothing</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>partitionFL'</span> <span class='hs-varid'>keepleft</span> <span class='hs-layout'>(</span><span class='hs-varid'>p'</span> <span class='hs-conop'>:<:</span> <span class='hs-varid'>middle</span><span class='hs-layout'>)</span> <span class='hs-varid'>right'</span> <span class='hs-varid'>ps</span>
<a name="line-72"></a> <span class='hs-conid'>Nothing</span> <span class='hs-keyglyph'>-></span> <span class='hs-keyword'>case</span> <span class='hs-varid'>commuteWhatWeCanRL</span> <span class='hs-layout'>(</span><span class='hs-varid'>right</span> <span class='hs-conop'>:></span> <span class='hs-varid'>p</span><span class='hs-layout'>)</span> <span class='hs-keyword'>of</span>
<a name="line-73"></a> <span class='hs-layout'>(</span><span class='hs-varid'>tomiddle</span> <span class='hs-conop'>:></span> <span class='hs-varid'>p'</span> <span class='hs-conop'>:></span> <span class='hs-varid'>right'</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>partitionFL'</span> <span class='hs-varid'>keepleft</span> <span class='hs-layout'>(</span><span class='hs-varid'>p'</span> <span class='hs-conop'>:<:</span> <span class='hs-varid'>tomiddle</span> <span class='hs-varop'>+<+</span> <span class='hs-varid'>middle</span><span class='hs-layout'>)</span> <span class='hs-varid'>right'</span> <span class='hs-varid'>ps</span>
<a name="line-74"></a> <span class='hs-keyglyph'>|</span> <span class='hs-varid'>otherwise</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>partitionFL'</span> <span class='hs-varid'>keepleft</span> <span class='hs-varid'>middle</span> <span class='hs-layout'>(</span><span class='hs-varid'>p</span> <span class='hs-conop'>:<:</span> <span class='hs-varid'>right</span><span class='hs-layout'>)</span> <span class='hs-varid'>ps</span>
<a name="line-75"></a>
<a name="line-76"></a>
<a name="line-77"></a><a name="partitionRL"></a><span class='hs-comment'>-- |split an 'RL' into "left" and "right" lists according to a predicate, using commutation as necessary.</span>
<a name="line-78"></a><span class='hs-comment'>-- If a patch does satisfy the predicate but cannot be commuted past one that does not satisfy</span>
<a name="line-79"></a><span class='hs-comment'>-- the predicate, it goes in the "left" list.</span>
<a name="line-80"></a><span class='hs-definition'>partitionRL</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Commute</span> <span class='hs-varid'>p</span>
<a name="line-81"></a> <span class='hs-keyglyph'>=></span> <span class='hs-layout'>(</span><span class='hs-conid'>FORALL</span><span class='hs-layout'>(</span><span class='hs-varid'>u</span> <span class='hs-varid'>v</span><span class='hs-layout'>)</span> <span class='hs-varid'>p</span> <span class='hs-conid'>C</span><span class='hs-layout'>(</span><span class='hs-varid'>u</span> <span class='hs-varid'>v</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Bool</span><span class='hs-layout'>)</span> <span class='hs-comment'>-- ^predicate; if true we would like the patch in the "right" list</span>
<a name="line-82"></a> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>RL</span> <span class='hs-varid'>p</span> <span class='hs-conid'>C</span><span class='hs-layout'>(</span><span class='hs-varid'>x</span> <span class='hs-varid'>y</span><span class='hs-layout'>)</span> <span class='hs-comment'>-- ^input 'RL'</span>
<a name="line-83"></a> <span class='hs-keyglyph'>-></span> <span class='hs-layout'>(</span><span class='hs-conid'>RL</span> <span class='hs-varid'>p</span> <span class='hs-conop'>:></span> <span class='hs-conid'>RL</span> <span class='hs-varid'>p</span><span class='hs-layout'>)</span> <span class='hs-conid'>C</span><span class='hs-layout'>(</span><span class='hs-varid'>x</span> <span class='hs-varid'>y</span><span class='hs-layout'>)</span> <span class='hs-comment'>-- ^"left" and "right" results</span>
<a name="line-84"></a>
<a name="line-85"></a><a name="partitionRL'"></a><span class='hs-comment'>-- optimise by using an accumulating parameter to track all the "left" patches that we've found so far</span>
<a name="line-86"></a><span class='hs-definition'>partitionRL'</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Commute</span> <span class='hs-varid'>p</span>
<a name="line-87"></a> <span class='hs-keyglyph'>=></span> <span class='hs-layout'>(</span><span class='hs-conid'>FORALL</span><span class='hs-layout'>(</span><span class='hs-varid'>u</span> <span class='hs-varid'>v</span><span class='hs-layout'>)</span> <span class='hs-varid'>p</span> <span class='hs-conid'>C</span><span class='hs-layout'>(</span><span class='hs-varid'>u</span> <span class='hs-varid'>v</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Bool</span><span class='hs-layout'>)</span>
<a name="line-88"></a> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>RL</span> <span class='hs-varid'>p</span> <span class='hs-conid'>C</span><span class='hs-layout'>(</span><span class='hs-varid'>x</span> <span class='hs-varid'>z</span><span class='hs-layout'>)</span>
<a name="line-89"></a> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>FL</span> <span class='hs-varid'>p</span> <span class='hs-conid'>C</span><span class='hs-layout'>(</span><span class='hs-varid'>z</span> <span class='hs-varid'>y</span><span class='hs-layout'>)</span> <span class='hs-comment'>-- the "left" patches found so far</span>
<a name="line-90"></a> <span class='hs-keyglyph'>-></span> <span class='hs-layout'>(</span><span class='hs-conid'>RL</span> <span class='hs-varid'>p</span> <span class='hs-conop'>:></span> <span class='hs-conid'>RL</span> <span class='hs-varid'>p</span><span class='hs-layout'>)</span> <span class='hs-conid'>C</span><span class='hs-layout'>(</span><span class='hs-varid'>x</span> <span class='hs-varid'>y</span><span class='hs-layout'>)</span>
<a name="line-91"></a>
<a name="line-92"></a><span class='hs-definition'>partitionRL</span> <span class='hs-varid'>keepright</span> <span class='hs-varid'>ps</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>partitionRL'</span> <span class='hs-varid'>keepright</span> <span class='hs-varid'>ps</span> <span class='hs-conid'>NilFL</span>
<a name="line-93"></a>
<a name="line-94"></a><span class='hs-definition'>partitionRL'</span> <span class='hs-keyword'>_</span> <span class='hs-conid'>NilRL</span> <span class='hs-varid'>qs</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>reverseFL</span> <span class='hs-varid'>qs</span> <span class='hs-conop'>:></span> <span class='hs-conid'>NilRL</span>
<a name="line-95"></a>
<a name="line-96"></a><span class='hs-definition'>partitionRL'</span> <span class='hs-varid'>keepright</span> <span class='hs-layout'>(</span><span class='hs-varid'>p</span> <span class='hs-conop'>:<:</span> <span class='hs-varid'>ps</span><span class='hs-layout'>)</span> <span class='hs-varid'>qs</span>
<a name="line-97"></a> <span class='hs-keyglyph'>|</span> <span class='hs-varid'>keepright</span> <span class='hs-varid'>p</span><span class='hs-layout'>,</span>
<a name="line-98"></a> <span class='hs-conid'>Right</span> <span class='hs-layout'>(</span><span class='hs-varid'>qs'</span> <span class='hs-conop'>:></span> <span class='hs-varid'>p'</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>commuteFLorComplain</span> <span class='hs-layout'>(</span><span class='hs-varid'>p</span> <span class='hs-conop'>:></span> <span class='hs-varid'>qs</span><span class='hs-layout'>)</span>
<a name="line-99"></a> <span class='hs-keyglyph'>=</span> <span class='hs-keyword'>case</span> <span class='hs-varid'>partitionRL'</span> <span class='hs-varid'>keepright</span> <span class='hs-varid'>ps</span> <span class='hs-varid'>qs'</span> <span class='hs-keyword'>of</span>
<a name="line-100"></a> <span class='hs-varid'>a</span> <span class='hs-conop'>:></span> <span class='hs-varid'>b</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>a</span> <span class='hs-conop'>:></span> <span class='hs-varid'>p'</span> <span class='hs-conop'>:<:</span> <span class='hs-varid'>b</span>
<a name="line-101"></a> <span class='hs-keyglyph'>|</span> <span class='hs-varid'>otherwise</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>partitionRL'</span> <span class='hs-varid'>keepright</span> <span class='hs-varid'>ps</span> <span class='hs-layout'>(</span><span class='hs-varid'>p</span> <span class='hs-conop'>:>:</span> <span class='hs-varid'>qs</span><span class='hs-layout'>)</span>
<a name="line-102"></a>
<a name="line-103"></a><a name="commuteWhatWeCanFL"></a><span class='hs-definition'>commuteWhatWeCanFL</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Commute</span> <span class='hs-varid'>p</span> <span class='hs-keyglyph'>=></span> <span class='hs-layout'>(</span><span class='hs-varid'>p</span> <span class='hs-conop'>:></span> <span class='hs-conid'>FL</span> <span class='hs-varid'>p</span><span class='hs-layout'>)</span> <span class='hs-conid'>C</span><span class='hs-layout'>(</span><span class='hs-varid'>x</span> <span class='hs-varid'>y</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>-></span> <span class='hs-layout'>(</span><span class='hs-conid'>FL</span> <span class='hs-varid'>p</span> <span class='hs-conop'>:></span> <span class='hs-varid'>p</span> <span class='hs-conop'>:></span> <span class='hs-conid'>FL</span> <span class='hs-varid'>p</span><span class='hs-layout'>)</span> <span class='hs-conid'>C</span><span class='hs-layout'>(</span><span class='hs-varid'>x</span> <span class='hs-varid'>y</span><span class='hs-layout'>)</span>
<a name="line-104"></a><span class='hs-definition'>commuteWhatWeCanFL</span> <span class='hs-layout'>(</span><span class='hs-varid'>p</span> <span class='hs-conop'>:></span> <span class='hs-varid'>x</span> <span class='hs-conop'>:>:</span> <span class='hs-varid'>xs</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span>
<a name="line-105"></a> <span class='hs-keyword'>case</span> <span class='hs-varid'>commute</span> <span class='hs-layout'>(</span><span class='hs-varid'>p</span> <span class='hs-conop'>:></span> <span class='hs-varid'>x</span><span class='hs-layout'>)</span> <span class='hs-keyword'>of</span>
<a name="line-106"></a> <span class='hs-conid'>Nothing</span> <span class='hs-keyglyph'>-></span> <span class='hs-keyword'>case</span> <span class='hs-varid'>commuteWhatWeCanFL</span> <span class='hs-layout'>(</span><span class='hs-varid'>x</span> <span class='hs-conop'>:></span> <span class='hs-varid'>xs</span><span class='hs-layout'>)</span> <span class='hs-keyword'>of</span>
<a name="line-107"></a> <span class='hs-varid'>xs1</span> <span class='hs-conop'>:></span> <span class='hs-varid'>x'</span> <span class='hs-conop'>:></span> <span class='hs-varid'>xs2</span> <span class='hs-keyglyph'>-></span> <span class='hs-keyword'>case</span> <span class='hs-varid'>commuteWhatWeCanFL</span> <span class='hs-layout'>(</span><span class='hs-varid'>p</span> <span class='hs-conop'>:></span> <span class='hs-varid'>xs1</span><span class='hs-layout'>)</span> <span class='hs-keyword'>of</span>
<a name="line-108"></a> <span class='hs-varid'>xs1'</span> <span class='hs-conop'>:></span> <span class='hs-varid'>p'</span> <span class='hs-conop'>:></span> <span class='hs-varid'>xs2'</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>xs1'</span> <span class='hs-conop'>:></span> <span class='hs-varid'>p'</span> <span class='hs-conop'>:></span> <span class='hs-varid'>xs2'</span> <span class='hs-varop'>+>+</span> <span class='hs-varid'>x'</span> <span class='hs-conop'>:>:</span> <span class='hs-varid'>xs2</span>
<a name="line-109"></a> <span class='hs-conid'>Just</span> <span class='hs-layout'>(</span><span class='hs-varid'>x'</span> <span class='hs-conop'>:></span> <span class='hs-varid'>p'</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>-></span> <span class='hs-keyword'>case</span> <span class='hs-varid'>commuteWhatWeCanFL</span> <span class='hs-layout'>(</span><span class='hs-varid'>p'</span> <span class='hs-conop'>:></span> <span class='hs-varid'>xs</span><span class='hs-layout'>)</span> <span class='hs-keyword'>of</span>
<a name="line-110"></a> <span class='hs-varid'>a</span> <span class='hs-conop'>:></span> <span class='hs-varid'>p''</span> <span class='hs-conop'>:></span> <span class='hs-varid'>c</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>x'</span> <span class='hs-conop'>:>:</span> <span class='hs-varid'>a</span> <span class='hs-conop'>:></span> <span class='hs-varid'>p''</span> <span class='hs-conop'>:></span> <span class='hs-varid'>c</span>
<a name="line-111"></a><span class='hs-definition'>commuteWhatWeCanFL</span> <span class='hs-layout'>(</span><span class='hs-varid'>y</span> <span class='hs-conop'>:></span> <span class='hs-conid'>NilFL</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>NilFL</span> <span class='hs-conop'>:></span> <span class='hs-varid'>y</span> <span class='hs-conop'>:></span> <span class='hs-conid'>NilFL</span>
<a name="line-112"></a>
<a name="line-113"></a><a name="commuteWhatWeCanRL"></a><span class='hs-definition'>commuteWhatWeCanRL</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Commute</span> <span class='hs-varid'>p</span> <span class='hs-keyglyph'>=></span> <span class='hs-layout'>(</span><span class='hs-conid'>RL</span> <span class='hs-varid'>p</span> <span class='hs-conop'>:></span> <span class='hs-varid'>p</span><span class='hs-layout'>)</span> <span class='hs-conid'>C</span><span class='hs-layout'>(</span><span class='hs-varid'>x</span> <span class='hs-varid'>y</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>-></span> <span class='hs-layout'>(</span><span class='hs-conid'>RL</span> <span class='hs-varid'>p</span> <span class='hs-conop'>:></span> <span class='hs-varid'>p</span> <span class='hs-conop'>:></span> <span class='hs-conid'>RL</span> <span class='hs-varid'>p</span><span class='hs-layout'>)</span> <span class='hs-conid'>C</span><span class='hs-layout'>(</span><span class='hs-varid'>x</span> <span class='hs-varid'>y</span><span class='hs-layout'>)</span>
<a name="line-114"></a><span class='hs-definition'>commuteWhatWeCanRL</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>genCommuteWhatWeCanRL</span> <span class='hs-varid'>commute</span>
<a name="line-115"></a>
<a name="line-116"></a><a name="genCommuteWhatWeCanRL"></a><span class='hs-definition'>genCommuteWhatWeCanRL</span> <span class='hs-keyglyph'>::</span> <span class='hs-layout'>(</span><span class='hs-conid'>FORALL</span><span class='hs-layout'>(</span><span class='hs-varid'>a</span> <span class='hs-varid'>b</span><span class='hs-layout'>)</span> <span class='hs-layout'>(</span><span class='hs-layout'>(</span><span class='hs-varid'>p</span> <span class='hs-conop'>:></span> <span class='hs-varid'>p</span><span class='hs-layout'>)</span> <span class='hs-conid'>C</span><span class='hs-layout'>(</span><span class='hs-varid'>a</span> <span class='hs-varid'>b</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Maybe</span> <span class='hs-layout'>(</span><span class='hs-layout'>(</span><span class='hs-varid'>p</span> <span class='hs-conop'>:></span> <span class='hs-varid'>p</span><span class='hs-layout'>)</span> <span class='hs-conid'>C</span><span class='hs-layout'>(</span><span class='hs-varid'>a</span> <span class='hs-varid'>b</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span>
<a name="line-117"></a> <span class='hs-keyglyph'>-></span> <span class='hs-layout'>(</span><span class='hs-conid'>RL</span> <span class='hs-varid'>p</span> <span class='hs-conop'>:></span> <span class='hs-varid'>p</span><span class='hs-layout'>)</span> <span class='hs-conid'>C</span><span class='hs-layout'>(</span><span class='hs-varid'>x</span> <span class='hs-varid'>y</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>-></span> <span class='hs-layout'>(</span><span class='hs-conid'>RL</span> <span class='hs-varid'>p</span> <span class='hs-conop'>:></span> <span class='hs-varid'>p</span> <span class='hs-conop'>:></span> <span class='hs-conid'>RL</span> <span class='hs-varid'>p</span><span class='hs-layout'>)</span> <span class='hs-conid'>C</span><span class='hs-layout'>(</span><span class='hs-varid'>x</span> <span class='hs-varid'>y</span><span class='hs-layout'>)</span>
<a name="line-118"></a><span class='hs-definition'>genCommuteWhatWeCanRL</span> <span class='hs-varid'>com</span> <span class='hs-layout'>(</span><span class='hs-varid'>x</span> <span class='hs-conop'>:<:</span> <span class='hs-varid'>xs</span> <span class='hs-conop'>:></span> <span class='hs-varid'>p</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span>
<a name="line-119"></a> <span class='hs-keyword'>case</span> <span class='hs-varid'>com</span> <span class='hs-layout'>(</span><span class='hs-varid'>x</span> <span class='hs-conop'>:></span> <span class='hs-varid'>p</span><span class='hs-layout'>)</span> <span class='hs-keyword'>of</span>
<a name="line-120"></a> <span class='hs-conid'>Nothing</span> <span class='hs-keyglyph'>-></span> <span class='hs-keyword'>case</span> <span class='hs-varid'>genCommuteWhatWeCanRL</span> <span class='hs-varid'>com</span> <span class='hs-layout'>(</span><span class='hs-varid'>xs</span> <span class='hs-conop'>:></span> <span class='hs-varid'>x</span><span class='hs-layout'>)</span> <span class='hs-keyword'>of</span>
<a name="line-121"></a> <span class='hs-varid'>xs1</span> <span class='hs-conop'>:></span> <span class='hs-varid'>x'</span> <span class='hs-conop'>:></span> <span class='hs-varid'>xs2</span> <span class='hs-keyglyph'>-></span> <span class='hs-keyword'>case</span> <span class='hs-varid'>genCommuteWhatWeCanRL</span> <span class='hs-varid'>com</span> <span class='hs-layout'>(</span><span class='hs-varid'>xs2</span> <span class='hs-conop'>:></span> <span class='hs-varid'>p</span><span class='hs-layout'>)</span> <span class='hs-keyword'>of</span>
<a name="line-122"></a> <span class='hs-varid'>xs1'</span> <span class='hs-conop'>:></span> <span class='hs-varid'>p'</span> <span class='hs-conop'>:></span> <span class='hs-varid'>xs2'</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>xs1'</span> <span class='hs-varop'>+<+</span> <span class='hs-varid'>x'</span> <span class='hs-conop'>:<:</span> <span class='hs-varid'>xs1</span> <span class='hs-conop'>:></span> <span class='hs-varid'>p'</span> <span class='hs-conop'>:></span> <span class='hs-varid'>xs2'</span>
<a name="line-123"></a> <span class='hs-conid'>Just</span> <span class='hs-layout'>(</span><span class='hs-varid'>p'</span> <span class='hs-conop'>:></span> <span class='hs-varid'>x'</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>-></span> <span class='hs-keyword'>case</span> <span class='hs-varid'>genCommuteWhatWeCanRL</span> <span class='hs-varid'>com</span> <span class='hs-layout'>(</span><span class='hs-varid'>xs</span> <span class='hs-conop'>:></span> <span class='hs-varid'>p'</span><span class='hs-layout'>)</span> <span class='hs-keyword'>of</span>
<a name="line-124"></a> <span class='hs-varid'>a</span> <span class='hs-conop'>:></span> <span class='hs-varid'>p''</span> <span class='hs-conop'>:></span> <span class='hs-varid'>c</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>a</span> <span class='hs-conop'>:></span> <span class='hs-varid'>p''</span> <span class='hs-conop'>:></span> <span class='hs-varid'>x'</span> <span class='hs-conop'>:<:</span> <span class='hs-varid'>c</span>
<a name="line-125"></a><span class='hs-definition'>genCommuteWhatWeCanRL</span> <span class='hs-keyword'>_</span> <span class='hs-layout'>(</span><span class='hs-conid'>NilRL</span> <span class='hs-conop'>:></span> <span class='hs-varid'>y</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>NilRL</span> <span class='hs-conop'>:></span> <span class='hs-varid'>y</span> <span class='hs-conop'>:></span> <span class='hs-conid'>NilRL</span>
<a name="line-126"></a>
<a name="line-127"></a>
<a name="line-128"></a><a name="removeCommon"></a><span class='hs-definition'>removeCommon</span> <span class='hs-keyglyph'>::</span> <span class='hs-layout'>(</span><span class='hs-conid'>MyEq</span> <span class='hs-varid'>p</span><span class='hs-layout'>,</span> <span class='hs-conid'>Commute</span> <span class='hs-varid'>p</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=></span> <span class='hs-layout'>(</span><span class='hs-conid'>FL</span> <span class='hs-varid'>p</span> <span class='hs-conop'>:\/:</span> <span class='hs-conid'>FL</span> <span class='hs-varid'>p</span><span class='hs-layout'>)</span> <span class='hs-conid'>C</span><span class='hs-layout'>(</span><span class='hs-varid'>x</span> <span class='hs-varid'>y</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>-></span> <span class='hs-layout'>(</span><span class='hs-conid'>FL</span> <span class='hs-varid'>p</span> <span class='hs-conop'>:\/:</span> <span class='hs-conid'>FL</span> <span class='hs-varid'>p</span><span class='hs-layout'>)</span> <span class='hs-conid'>C</span><span class='hs-layout'>(</span><span class='hs-varid'>x</span> <span class='hs-varid'>y</span><span class='hs-layout'>)</span>
<a name="line-129"></a><span class='hs-definition'>removeCommon</span> <span class='hs-layout'>(</span><span class='hs-varid'>xs</span> <span class='hs-conop'>:\/:</span> <span class='hs-conid'>NilFL</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>xs</span> <span class='hs-conop'>:\/:</span> <span class='hs-conid'>NilFL</span>
<a name="line-130"></a><span class='hs-definition'>removeCommon</span> <span class='hs-layout'>(</span><span class='hs-conid'>NilFL</span> <span class='hs-conop'>:\/:</span> <span class='hs-varid'>xs</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>NilFL</span> <span class='hs-conop'>:\/:</span> <span class='hs-varid'>xs</span>
<a name="line-131"></a><span class='hs-definition'>removeCommon</span> <span class='hs-layout'>(</span><span class='hs-varid'>xs</span> <span class='hs-conop'>:\/:</span> <span class='hs-varid'>ys</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>rc</span> <span class='hs-varid'>xs</span> <span class='hs-layout'>(</span><span class='hs-varid'>headPermutationsFL</span> <span class='hs-varid'>ys</span><span class='hs-layout'>)</span>
<a name="line-132"></a> <span class='hs-keyword'>where</span> <span class='hs-varid'>rc</span> <span class='hs-keyglyph'>::</span> <span class='hs-layout'>(</span><span class='hs-conid'>MyEq</span> <span class='hs-varid'>p</span><span class='hs-layout'>,</span> <span class='hs-conid'>Commute</span> <span class='hs-varid'>p</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=></span> <span class='hs-conid'>FL</span> <span class='hs-varid'>p</span> <span class='hs-conid'>C</span><span class='hs-layout'>(</span><span class='hs-varid'>x</span> <span class='hs-varid'>y</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>-></span> <span class='hs-keyglyph'>[</span><span class='hs-layout'>(</span><span class='hs-varid'>p</span><span class='hs-conop'>:></span><span class='hs-conid'>FL</span> <span class='hs-varid'>p</span><span class='hs-layout'>)</span> <span class='hs-conid'>C</span><span class='hs-layout'>(</span><span class='hs-varid'>x</span> <span class='hs-varid'>z</span><span class='hs-layout'>)</span><span class='hs-keyglyph'>]</span> <span class='hs-keyglyph'>-></span> <span class='hs-layout'>(</span><span class='hs-conid'>FL</span> <span class='hs-varid'>p</span> <span class='hs-conop'>:\/:</span> <span class='hs-conid'>FL</span> <span class='hs-varid'>p</span><span class='hs-layout'>)</span> <span class='hs-conid'>C</span><span class='hs-layout'>(</span><span class='hs-varid'>y</span> <span class='hs-varid'>z</span><span class='hs-layout'>)</span>
<a name="line-133"></a> <span class='hs-varid'>rc</span> <span class='hs-varid'>nms</span> <span class='hs-layout'>(</span><span class='hs-layout'>(</span><span class='hs-varid'>n</span><span class='hs-conop'>:></span><span class='hs-varid'>ns</span><span class='hs-layout'>)</span><span class='hs-conop'>:</span><span class='hs-keyword'>_</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>|</span> <span class='hs-conid'>Just</span> <span class='hs-varid'>ms</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>removeFL</span> <span class='hs-varid'>n</span> <span class='hs-varid'>nms</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>removeCommon</span> <span class='hs-layout'>(</span><span class='hs-varid'>ms</span> <span class='hs-conop'>:\/:</span> <span class='hs-varid'>ns</span><span class='hs-layout'>)</span>
<a name="line-134"></a> <span class='hs-varid'>rc</span> <span class='hs-varid'>ms</span> <span class='hs-keyglyph'>[</span><span class='hs-varid'>n</span><span class='hs-conop'>:></span><span class='hs-varid'>ns</span><span class='hs-keyglyph'>]</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>ms</span> <span class='hs-conop'>:\/:</span> <span class='hs-varid'>n</span><span class='hs-conop'>:>:</span><span class='hs-varid'>ns</span>
<a name="line-135"></a> <span class='hs-varid'>rc</span> <span class='hs-varid'>ms</span> <span class='hs-layout'>(</span><span class='hs-keyword'>_</span><span class='hs-conop'>:</span><span class='hs-varid'>nss</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>rc</span> <span class='hs-varid'>ms</span> <span class='hs-varid'>nss</span>
<a name="line-136"></a> <span class='hs-varid'>rc</span> <span class='hs-keyword'>_</span> <span class='hs-conid'>[]</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>impossible</span> <span class='hs-comment'>-- because we already checked for NilFL case</span>
<a name="line-137"></a>
<a name="line-138"></a><a name="removeFL"></a><span class='hs-comment'>-- | 'removeFL' @x xs@ removes @x@ from @xs@ if @x@ can be commuted to its head.</span>
<a name="line-139"></a><span class='hs-comment'>-- Otherwise it returns 'Nothing'</span>
<a name="line-140"></a><span class='hs-definition'>removeFL</span> <span class='hs-keyglyph'>::</span> <span class='hs-layout'>(</span><span class='hs-conid'>MyEq</span> <span class='hs-varid'>p</span><span class='hs-layout'>,</span> <span class='hs-conid'>Commute</span> <span class='hs-varid'>p</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=></span> <span class='hs-varid'>p</span> <span class='hs-conid'>C</span><span class='hs-layout'>(</span><span class='hs-varid'>x</span> <span class='hs-varid'>y</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>FL</span> <span class='hs-varid'>p</span> <span class='hs-conid'>C</span><span class='hs-layout'>(</span><span class='hs-varid'>x</span> <span class='hs-varid'>z</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Maybe</span> <span class='hs-layout'>(</span><span class='hs-conid'>FL</span> <span class='hs-varid'>p</span> <span class='hs-conid'>C</span><span class='hs-layout'>(</span><span class='hs-varid'>y</span> <span class='hs-varid'>z</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span>
<a name="line-141"></a><span class='hs-definition'>removeFL</span> <span class='hs-varid'>x</span> <span class='hs-varid'>xs</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>r</span> <span class='hs-varid'>x</span> <span class='hs-varop'>$</span> <span class='hs-varid'>headPermutationsFL</span> <span class='hs-varid'>xs</span>
<a name="line-142"></a> <span class='hs-keyword'>where</span> <span class='hs-varid'>r</span> <span class='hs-keyglyph'>::</span> <span class='hs-layout'>(</span><span class='hs-conid'>MyEq</span> <span class='hs-varid'>p</span><span class='hs-layout'>,</span> <span class='hs-conid'>Commute</span> <span class='hs-varid'>p</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=></span> <span class='hs-varid'>p</span> <span class='hs-conid'>C</span><span class='hs-layout'>(</span><span class='hs-varid'>x</span> <span class='hs-varid'>y</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>-></span> <span class='hs-keyglyph'>[</span><span class='hs-layout'>(</span><span class='hs-varid'>p</span><span class='hs-conop'>:></span><span class='hs-conid'>FL</span> <span class='hs-varid'>p</span><span class='hs-layout'>)</span> <span class='hs-conid'>C</span><span class='hs-layout'>(</span><span class='hs-varid'>x</span> <span class='hs-varid'>z</span><span class='hs-layout'>)</span><span class='hs-keyglyph'>]</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Maybe</span> <span class='hs-layout'>(</span><span class='hs-conid'>FL</span> <span class='hs-varid'>p</span> <span class='hs-conid'>C</span><span class='hs-layout'>(</span><span class='hs-varid'>y</span> <span class='hs-varid'>z</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span>
<a name="line-143"></a> <span class='hs-varid'>r</span> <span class='hs-keyword'>_</span> <span class='hs-conid'>[]</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>Nothing</span>
<a name="line-144"></a> <span class='hs-varid'>r</span> <span class='hs-varid'>z</span> <span class='hs-layout'>(</span><span class='hs-layout'>(</span><span class='hs-varid'>z'</span><span class='hs-conop'>:></span><span class='hs-varid'>zs</span><span class='hs-layout'>)</span><span class='hs-conop'>:</span><span class='hs-varid'>zss</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>|</span> <span class='hs-conid'>IsEq</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>z</span> <span class='hs-varop'>=\/=</span> <span class='hs-varid'>z'</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>Just</span> <span class='hs-varid'>zs</span>
<a name="line-145"></a> <span class='hs-keyglyph'>|</span> <span class='hs-varid'>otherwise</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>r</span> <span class='hs-varid'>z</span> <span class='hs-varid'>zss</span>
<a name="line-146"></a>
<a name="line-147"></a><a name="removeRL"></a><span class='hs-comment'>-- | 'removeRL' is like 'removeFL' except with 'RL'</span>
<a name="line-148"></a><span class='hs-definition'>removeRL</span> <span class='hs-keyglyph'>::</span> <span class='hs-layout'>(</span><span class='hs-conid'>MyEq</span> <span class='hs-varid'>p</span><span class='hs-layout'>,</span> <span class='hs-conid'>Commute</span> <span class='hs-varid'>p</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=></span> <span class='hs-varid'>p</span> <span class='hs-conid'>C</span><span class='hs-layout'>(</span><span class='hs-varid'>y</span> <span class='hs-varid'>z</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>RL</span> <span class='hs-varid'>p</span> <span class='hs-conid'>C</span><span class='hs-layout'>(</span><span class='hs-varid'>x</span> <span class='hs-varid'>z</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Maybe</span> <span class='hs-layout'>(</span><span class='hs-conid'>RL</span> <span class='hs-varid'>p</span> <span class='hs-conid'>C</span><span class='hs-layout'>(</span><span class='hs-varid'>x</span> <span class='hs-varid'>y</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span>
<a name="line-149"></a><span class='hs-definition'>removeRL</span> <span class='hs-varid'>x</span> <span class='hs-varid'>xs</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>r</span> <span class='hs-varid'>x</span> <span class='hs-varop'>$</span> <span class='hs-varid'>headPermutationsRL</span> <span class='hs-varid'>xs</span>
<a name="line-150"></a> <span class='hs-keyword'>where</span> <span class='hs-varid'>r</span> <span class='hs-keyglyph'>::</span> <span class='hs-layout'>(</span><span class='hs-conid'>MyEq</span> <span class='hs-varid'>p</span><span class='hs-layout'>,</span> <span class='hs-conid'>Commute</span> <span class='hs-varid'>p</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=></span> <span class='hs-varid'>p</span> <span class='hs-conid'>C</span><span class='hs-layout'>(</span><span class='hs-varid'>y</span> <span class='hs-varid'>z</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>-></span> <span class='hs-keyglyph'>[</span><span class='hs-conid'>RL</span> <span class='hs-varid'>p</span> <span class='hs-conid'>C</span><span class='hs-layout'>(</span><span class='hs-varid'>x</span> <span class='hs-varid'>z</span><span class='hs-layout'>)</span><span class='hs-keyglyph'>]</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Maybe</span> <span class='hs-layout'>(</span><span class='hs-conid'>RL</span> <span class='hs-varid'>p</span> <span class='hs-conid'>C</span><span class='hs-layout'>(</span><span class='hs-varid'>x</span> <span class='hs-varid'>y</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span>
<a name="line-151"></a> <span class='hs-varid'>r</span> <span class='hs-varid'>z</span> <span class='hs-layout'>(</span><span class='hs-layout'>(</span><span class='hs-varid'>z'</span><span class='hs-conop'>:<:</span><span class='hs-varid'>zs</span><span class='hs-layout'>)</span><span class='hs-conop'>:</span><span class='hs-varid'>zss</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>|</span> <span class='hs-conid'>IsEq</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>z</span> <span class='hs-varop'>=/\=</span> <span class='hs-varid'>z'</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>Just</span> <span class='hs-varid'>zs</span>
<a name="line-152"></a> <span class='hs-keyglyph'>|</span> <span class='hs-varid'>otherwise</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>r</span> <span class='hs-varid'>z</span> <span class='hs-varid'>zss</span>
<a name="line-153"></a> <span class='hs-varid'>r</span> <span class='hs-keyword'>_</span> <span class='hs-keyword'>_</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>Nothing</span>
<a name="line-154"></a>
<a name="line-155"></a><a name="removeSubsequenceFL"></a><span class='hs-comment'>-- | 'removeSubsequenceFL' @ab abc@ returns @Just c'@ where all the patches in</span>
<a name="line-156"></a><span class='hs-comment'>-- @ab@ have been commuted out of it, if possible. If this is not possible</span>
<a name="line-157"></a><span class='hs-comment'>-- for any reason (the set of patches @ab@ is not actually a subset of @abc@,</span>
<a name="line-158"></a><span class='hs-comment'>-- or they can't be commuted out) we return 'Nothing'.</span>
<a name="line-159"></a><span class='hs-definition'>removeSubsequenceFL</span> <span class='hs-keyglyph'>::</span> <span class='hs-layout'>(</span><span class='hs-conid'>MyEq</span> <span class='hs-varid'>p</span><span class='hs-layout'>,</span> <span class='hs-conid'>Commute</span> <span class='hs-varid'>p</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=></span> <span class='hs-conid'>FL</span> <span class='hs-varid'>p</span> <span class='hs-conid'>C</span><span class='hs-layout'>(</span><span class='hs-varid'>a</span> <span class='hs-varid'>b</span><span class='hs-layout'>)</span>
<a name="line-160"></a> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>FL</span> <span class='hs-varid'>p</span> <span class='hs-conid'>C</span><span class='hs-layout'>(</span><span class='hs-varid'>a</span> <span class='hs-varid'>c</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Maybe</span> <span class='hs-layout'>(</span><span class='hs-conid'>FL</span> <span class='hs-varid'>p</span> <span class='hs-conid'>C</span><span class='hs-layout'>(</span><span class='hs-varid'>b</span> <span class='hs-varid'>c</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span>
<a name="line-161"></a><span class='hs-definition'>removeSubsequenceFL</span> <span class='hs-varid'>a</span> <span class='hs-varid'>b</span> <span class='hs-keyglyph'>|</span> <span class='hs-varid'>lengthFL</span> <span class='hs-varid'>a</span> <span class='hs-varop'>></span> <span class='hs-varid'>lengthFL</span> <span class='hs-varid'>b</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>Nothing</span>
<a name="line-162"></a> <span class='hs-keyglyph'>|</span> <span class='hs-varid'>otherwise</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>rsFL</span> <span class='hs-varid'>a</span> <span class='hs-varid'>b</span>
<a name="line-163"></a> <span class='hs-keyword'>where</span> <span class='hs-varid'>rsFL</span> <span class='hs-keyglyph'>::</span> <span class='hs-layout'>(</span><span class='hs-conid'>MyEq</span> <span class='hs-varid'>p</span><span class='hs-layout'>,</span> <span class='hs-conid'>Commute</span> <span class='hs-varid'>p</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=></span> <span class='hs-conid'>FL</span> <span class='hs-varid'>p</span> <span class='hs-conid'>C</span><span class='hs-layout'>(</span><span class='hs-varid'>a</span> <span class='hs-varid'>b</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>FL</span> <span class='hs-varid'>p</span> <span class='hs-conid'>C</span><span class='hs-layout'>(</span><span class='hs-varid'>a</span> <span class='hs-varid'>c</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Maybe</span> <span class='hs-layout'>(</span><span class='hs-conid'>FL</span> <span class='hs-varid'>p</span> <span class='hs-conid'>C</span><span class='hs-layout'>(</span><span class='hs-varid'>b</span> <span class='hs-varid'>c</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span>
<a name="line-164"></a> <span class='hs-varid'>rsFL</span> <span class='hs-conid'>NilFL</span> <span class='hs-varid'>ys</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>Just</span> <span class='hs-varid'>ys</span>
<a name="line-165"></a> <span class='hs-varid'>rsFL</span> <span class='hs-layout'>(</span><span class='hs-varid'>x</span><span class='hs-conop'>:>:</span><span class='hs-varid'>xs</span><span class='hs-layout'>)</span> <span class='hs-varid'>yys</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>removeFL</span> <span class='hs-varid'>x</span> <span class='hs-varid'>yys</span> <span class='hs-varop'>>>=</span> <span class='hs-varid'>removeSubsequenceFL</span> <span class='hs-varid'>xs</span>
<a name="line-166"></a>
<a name="line-167"></a><a name="removeSubsequenceRL"></a><span class='hs-comment'>-- | 'removeSubsequenceRL' is like @removeSubsequenceFL@ except that it works</span>
<a name="line-168"></a><span class='hs-comment'>-- on 'RL'</span>
<a name="line-169"></a><span class='hs-definition'>removeSubsequenceRL</span> <span class='hs-keyglyph'>::</span> <span class='hs-layout'>(</span><span class='hs-conid'>MyEq</span> <span class='hs-varid'>p</span><span class='hs-layout'>,</span> <span class='hs-conid'>Commute</span> <span class='hs-varid'>p</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=></span> <span class='hs-conid'>RL</span> <span class='hs-varid'>p</span> <span class='hs-conid'>C</span><span class='hs-layout'>(</span><span class='hs-varid'>ab</span> <span class='hs-varid'>abc</span><span class='hs-layout'>)</span>
<a name="line-170"></a> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>RL</span> <span class='hs-varid'>p</span> <span class='hs-conid'>C</span><span class='hs-layout'>(</span><span class='hs-varid'>a</span> <span class='hs-varid'>abc</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Maybe</span> <span class='hs-layout'>(</span><span class='hs-conid'>RL</span> <span class='hs-varid'>p</span> <span class='hs-conid'>C</span><span class='hs-layout'>(</span><span class='hs-varid'>a</span> <span class='hs-varid'>ab</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span>
<a name="line-171"></a><span class='hs-definition'>removeSubsequenceRL</span> <span class='hs-varid'>a</span> <span class='hs-varid'>b</span> <span class='hs-keyglyph'>|</span> <span class='hs-varid'>lengthRL</span> <span class='hs-varid'>a</span> <span class='hs-varop'>></span> <span class='hs-varid'>lengthRL</span> <span class='hs-varid'>b</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>Nothing</span>
<a name="line-172"></a> <span class='hs-keyglyph'>|</span> <span class='hs-varid'>otherwise</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>rsRL</span> <span class='hs-varid'>a</span> <span class='hs-varid'>b</span>
<a name="line-173"></a> <span class='hs-keyword'>where</span> <span class='hs-varid'>rsRL</span> <span class='hs-keyglyph'>::</span> <span class='hs-layout'>(</span><span class='hs-conid'>MyEq</span> <span class='hs-varid'>p</span><span class='hs-layout'>,</span> <span class='hs-conid'>Commute</span> <span class='hs-varid'>p</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=></span> <span class='hs-conid'>RL</span> <span class='hs-varid'>p</span> <span class='hs-conid'>C</span><span class='hs-layout'>(</span><span class='hs-varid'>ab</span> <span class='hs-varid'>abc</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>RL</span> <span class='hs-varid'>p</span> <span class='hs-conid'>C</span><span class='hs-layout'>(</span><span class='hs-varid'>a</span> <span class='hs-varid'>abc</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Maybe</span> <span class='hs-layout'>(</span><span class='hs-conid'>RL</span> <span class='hs-varid'>p</span> <span class='hs-conid'>C</span><span class='hs-layout'>(</span><span class='hs-varid'>a</span> <span class='hs-varid'>ab</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span>
<a name="line-174"></a> <span class='hs-varid'>rsRL</span> <span class='hs-conid'>NilRL</span> <span class='hs-varid'>ys</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>Just</span> <span class='hs-varid'>ys</span>
<a name="line-175"></a> <span class='hs-varid'>rsRL</span> <span class='hs-layout'>(</span><span class='hs-varid'>x</span><span class='hs-conop'>:<:</span><span class='hs-varid'>xs</span><span class='hs-layout'>)</span> <span class='hs-varid'>yys</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>removeRL</span> <span class='hs-varid'>x</span> <span class='hs-varid'>yys</span> <span class='hs-varop'>>>=</span> <span class='hs-varid'>removeSubsequenceRL</span> <span class='hs-varid'>xs</span>
<a name="line-176"></a>
<a name="line-177"></a><a name="simpleHeadPermutationsFL"></a><span class='hs-comment'>-- | This is a minor variant of 'headPermutationsFL' with each permutation</span>
<a name="line-178"></a><span class='hs-comment'>-- is simply returned as a 'FL'</span>
<a name="line-179"></a><span class='hs-definition'>simpleHeadPermutationsFL</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Commute</span> <span class='hs-varid'>p</span> <span class='hs-keyglyph'>=></span> <span class='hs-conid'>FL</span> <span class='hs-varid'>p</span> <span class='hs-conid'>C</span><span class='hs-layout'>(</span><span class='hs-varid'>x</span> <span class='hs-varid'>y</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>-></span> <span class='hs-keyglyph'>[</span><span class='hs-conid'>FL</span> <span class='hs-varid'>p</span> <span class='hs-conid'>C</span><span class='hs-layout'>(</span><span class='hs-varid'>x</span> <span class='hs-varid'>y</span><span class='hs-layout'>)</span><span class='hs-keyglyph'>]</span>
<a name="line-180"></a><span class='hs-definition'>simpleHeadPermutationsFL</span> <span class='hs-varid'>ps</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>map</span> <span class='hs-layout'>(</span><span class='hs-keyglyph'>\</span> <span class='hs-layout'>(</span><span class='hs-varid'>x</span><span class='hs-conop'>:></span><span class='hs-varid'>xs</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>x</span><span class='hs-conop'>:>:</span><span class='hs-varid'>xs</span><span class='hs-layout'>)</span> <span class='hs-varop'>$</span> <span class='hs-varid'>headPermutationsFL</span> <span class='hs-varid'>ps</span>
<a name="line-181"></a>
<a name="line-182"></a><a name="headPermutationsFL"></a><span class='hs-comment'>-- | 'headPermutationsFL' @p:>:ps@ returns all the permutations of the list</span>
<a name="line-183"></a><span class='hs-comment'>-- in which one element of @ps@ is commuted past @p@</span>
<a name="line-184"></a><span class='hs-comment'>--</span>
<a name="line-185"></a><span class='hs-comment'>-- Suppose we have a sequence of patches</span>
<a name="line-186"></a><span class='hs-comment'>--</span>
<a name="line-187"></a><span class='hs-comment'>-- > X h a y s-t-c k</span>
<a name="line-188"></a><span class='hs-comment'>--</span>
<a name="line-189"></a><span class='hs-comment'>-- Suppose furthermore that the patch @c@ depends on @t@, which in turn</span>
<a name="line-190"></a><span class='hs-comment'>-- depends on @s@. This function will return</span>
<a name="line-191"></a><span class='hs-comment'>--</span>
<a name="line-192"></a><span class='hs-comment'>-- > X :> h a y s t c k</span>
<a name="line-193"></a><span class='hs-comment'>-- > h :> X a y s t c k</span>
<a name="line-194"></a><span class='hs-comment'>-- > a :> X h y s t c k</span>
<a name="line-195"></a><span class='hs-comment'>-- > y :> X h a s t c k</span>
<a name="line-196"></a><span class='hs-comment'>-- > s :> X h a y t c k</span>
<a name="line-197"></a><span class='hs-comment'>-- > k :> X h a y s t c</span>
<a name="line-198"></a><span class='hs-definition'>headPermutationsFL</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Commute</span> <span class='hs-varid'>p</span> <span class='hs-keyglyph'>=></span> <span class='hs-conid'>FL</span> <span class='hs-varid'>p</span> <span class='hs-conid'>C</span><span class='hs-layout'>(</span><span class='hs-varid'>x</span> <span class='hs-varid'>y</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>-></span> <span class='hs-keyglyph'>[</span><span class='hs-layout'>(</span><span class='hs-varid'>p</span> <span class='hs-conop'>:></span> <span class='hs-conid'>FL</span> <span class='hs-varid'>p</span><span class='hs-layout'>)</span> <span class='hs-conid'>C</span><span class='hs-layout'>(</span><span class='hs-varid'>x</span> <span class='hs-varid'>y</span><span class='hs-layout'>)</span><span class='hs-keyglyph'>]</span>
<a name="line-199"></a><span class='hs-definition'>headPermutationsFL</span> <span class='hs-conid'>NilFL</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>[]</span>
<a name="line-200"></a><span class='hs-definition'>headPermutationsFL</span> <span class='hs-layout'>(</span><span class='hs-varid'>p</span><span class='hs-conop'>:>:</span><span class='hs-varid'>ps</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span>
<a name="line-201"></a> <span class='hs-layout'>(</span><span class='hs-varid'>p</span><span class='hs-conop'>:></span><span class='hs-varid'>ps</span><span class='hs-layout'>)</span> <span class='hs-conop'>:</span> <span class='hs-varid'>mapMaybe</span> <span class='hs-layout'>(</span><span class='hs-varid'>swapfirstFL</span><span class='hs-varop'>.</span><span class='hs-layout'>(</span><span class='hs-varid'>p</span><span class='hs-conop'>:></span><span class='hs-layout'>)</span><span class='hs-layout'>)</span> <span class='hs-layout'>(</span><span class='hs-varid'>headPermutationsFL</span> <span class='hs-varid'>ps</span><span class='hs-layout'>)</span>
<a name="line-202"></a> <span class='hs-keyword'>where</span> <span class='hs-varid'>swapfirstFL</span> <span class='hs-layout'>(</span><span class='hs-varid'>p1</span><span class='hs-conop'>:></span><span class='hs-varid'>p2</span><span class='hs-conop'>:></span><span class='hs-varid'>xs</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-keyword'>do</span> <span class='hs-varid'>p2'</span><span class='hs-conop'>:></span><span class='hs-varid'>p1'</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>commute</span> <span class='hs-layout'>(</span><span class='hs-varid'>p1</span><span class='hs-conop'>:></span><span class='hs-varid'>p2</span><span class='hs-layout'>)</span>
<a name="line-203"></a> <span class='hs-conid'>Just</span> <span class='hs-varop'>$</span> <span class='hs-varid'>p2'</span><span class='hs-conop'>:></span><span class='hs-varid'>p1'</span><span class='hs-conop'>:>:</span><span class='hs-varid'>xs</span>
<a name="line-204"></a>
<a name="line-205"></a><a name="headPermutationsRL"></a><span class='hs-comment'>-- | 'headPermutationsRL' is like 'headPermutationsFL', except that we</span>
<a name="line-206"></a><span class='hs-comment'>-- operate on an 'RL' (in other words, we are pushing things to the end of a</span>
<a name="line-207"></a><span class='hs-comment'>-- patch sequence instead of to the beginning).</span>
<a name="line-208"></a><span class='hs-definition'>headPermutationsRL</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Commute</span> <span class='hs-varid'>p</span> <span class='hs-keyglyph'>=></span> <span class='hs-conid'>RL</span> <span class='hs-varid'>p</span> <span class='hs-conid'>C</span><span class='hs-layout'>(</span><span class='hs-varid'>x</span> <span class='hs-varid'>y</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>-></span> <span class='hs-keyglyph'>[</span><span class='hs-conid'>RL</span> <span class='hs-varid'>p</span> <span class='hs-conid'>C</span><span class='hs-layout'>(</span><span class='hs-varid'>x</span> <span class='hs-varid'>y</span><span class='hs-layout'>)</span><span class='hs-keyglyph'>]</span>
<a name="line-209"></a><span class='hs-definition'>headPermutationsRL</span> <span class='hs-conid'>NilRL</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>[]</span>
<a name="line-210"></a><span class='hs-definition'>headPermutationsRL</span> <span class='hs-layout'>(</span><span class='hs-varid'>p</span><span class='hs-conop'>:<:</span><span class='hs-varid'>ps</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span>
<a name="line-211"></a> <span class='hs-layout'>(</span><span class='hs-varid'>p</span><span class='hs-conop'>:<:</span><span class='hs-varid'>ps</span><span class='hs-layout'>)</span> <span class='hs-conop'>:</span> <span class='hs-varid'>mapMaybe</span> <span class='hs-layout'>(</span><span class='hs-varid'>swapfirstRL</span><span class='hs-varop'>.</span><span class='hs-layout'>(</span><span class='hs-varid'>p</span><span class='hs-conop'>:<:</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span> <span class='hs-layout'>(</span><span class='hs-varid'>headPermutationsRL</span> <span class='hs-varid'>ps</span><span class='hs-layout'>)</span>
<a name="line-212"></a> <span class='hs-keyword'>where</span> <span class='hs-varid'>swapfirstRL</span> <span class='hs-layout'>(</span><span class='hs-varid'>p1</span><span class='hs-conop'>:<:</span><span class='hs-varid'>p2</span><span class='hs-conop'>:<:</span><span class='hs-varid'>xs</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-keyword'>do</span> <span class='hs-varid'>p1'</span><span class='hs-conop'>:></span><span class='hs-varid'>p2'</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>commute</span> <span class='hs-layout'>(</span><span class='hs-varid'>p2</span><span class='hs-conop'>:></span><span class='hs-varid'>p1</span><span class='hs-layout'>)</span>
<a name="line-213"></a> <span class='hs-conid'>Just</span> <span class='hs-varop'>$</span> <span class='hs-varid'>p2'</span><span class='hs-conop'>:<:</span><span class='hs-varid'>p1'</span><span class='hs-conop'>:<:</span><span class='hs-varid'>xs</span>
<a name="line-214"></a> <span class='hs-varid'>swapfirstRL</span> <span class='hs-keyword'>_</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>Nothing</span>
<a name="line-215"></a>
<a name="line-216"></a><a name="instance%20MyEq%20(FL%20p)"></a><span class='hs-keyword'>instance</span> <span class='hs-layout'>(</span><span class='hs-conid'>MyEq</span> <span class='hs-varid'>p</span><span class='hs-layout'>,</span> <span class='hs-conid'>Commute</span> <span class='hs-varid'>p</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=></span> <span class='hs-conid'>MyEq</span> <span class='hs-layout'>(</span><span class='hs-conid'>FL</span> <span class='hs-varid'>p</span><span class='hs-layout'>)</span> <span class='hs-keyword'>where</span>
<a name="line-217"></a> <span class='hs-varid'>a</span> <span class='hs-varop'>=\/=</span> <span class='hs-varid'>b</span> <span class='hs-keyglyph'>|</span> <span class='hs-varid'>lengthFL</span> <span class='hs-varid'>a</span> <span class='hs-varop'>/=</span> <span class='hs-varid'>lengthFL</span> <span class='hs-varid'>b</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>NotEq</span>
<a name="line-218"></a> <span class='hs-keyglyph'>|</span> <span class='hs-varid'>otherwise</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>cmpSameLength</span> <span class='hs-varid'>a</span> <span class='hs-varid'>b</span>
<a name="line-219"></a> <span class='hs-keyword'>where</span> <span class='hs-varid'>cmpSameLength</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>FL</span> <span class='hs-varid'>p</span> <span class='hs-conid'>C</span><span class='hs-layout'>(</span><span class='hs-varid'>x</span> <span class='hs-varid'>y</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>FL</span> <span class='hs-varid'>p</span> <span class='hs-conid'>C</span><span class='hs-layout'>(</span><span class='hs-varid'>x</span> <span class='hs-varid'>z</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>EqCheck</span> <span class='hs-conid'>C</span><span class='hs-layout'>(</span><span class='hs-varid'>y</span> <span class='hs-varid'>z</span><span class='hs-layout'>)</span>
<a name="line-220"></a> <span class='hs-varid'>cmpSameLength</span> <span class='hs-layout'>(</span><span class='hs-varid'>x</span><span class='hs-conop'>:>:</span><span class='hs-varid'>xs</span><span class='hs-layout'>)</span> <span class='hs-varid'>xys</span> <span class='hs-keyglyph'>|</span> <span class='hs-conid'>Just</span> <span class='hs-varid'>ys</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>removeFL</span> <span class='hs-varid'>x</span> <span class='hs-varid'>xys</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>cmpSameLength</span> <span class='hs-varid'>xs</span> <span class='hs-varid'>ys</span>
<a name="line-221"></a> <span class='hs-varid'>cmpSameLength</span> <span class='hs-conid'>NilFL</span> <span class='hs-conid'>NilFL</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>IsEq</span>
<a name="line-222"></a> <span class='hs-varid'>cmpSameLength</span> <span class='hs-keyword'>_</span> <span class='hs-keyword'>_</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>NotEq</span>
<a name="line-223"></a> <span class='hs-varid'>xs</span> <span class='hs-varop'>=/\=</span> <span class='hs-varid'>ys</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>reverseFL</span> <span class='hs-varid'>xs</span> <span class='hs-varop'>=/\=</span> <span class='hs-varid'>reverseFL</span> <span class='hs-varid'>ys</span>
<a name="line-224"></a>
<a name="line-225"></a><a name="instance%20Invert%20(FL%20p)"></a><span class='hs-keyword'>instance</span> <span class='hs-layout'>(</span><span class='hs-conid'>Invert</span> <span class='hs-varid'>p</span><span class='hs-layout'>,</span> <span class='hs-conid'>Commute</span> <span class='hs-varid'>p</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=></span> <span class='hs-conid'>Invert</span> <span class='hs-layout'>(</span><span class='hs-conid'>FL</span> <span class='hs-varid'>p</span><span class='hs-layout'>)</span> <span class='hs-keyword'>where</span>
<a name="line-226"></a> <span class='hs-varid'>invert</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>reverseRL</span> <span class='hs-varop'>.</span> <span class='hs-varid'>invertFL</span>
<a name="line-227"></a>
<a name="line-228"></a><a name="instance%20MyEq%20(RL%20p)"></a><span class='hs-keyword'>instance</span> <span class='hs-layout'>(</span><span class='hs-conid'>MyEq</span> <span class='hs-varid'>p</span><span class='hs-layout'>,</span> <span class='hs-conid'>Commute</span> <span class='hs-varid'>p</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=></span> <span class='hs-conid'>MyEq</span> <span class='hs-layout'>(</span><span class='hs-conid'>RL</span> <span class='hs-varid'>p</span><span class='hs-layout'>)</span> <span class='hs-keyword'>where</span>
<a name="line-229"></a> <span class='hs-varid'>unsafeCompare</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>bug</span> <span class='hs-str'>"Buggy use of unsafeCompare on RL"</span>
<a name="line-230"></a> <span class='hs-varid'>a</span> <span class='hs-varop'>=/\=</span> <span class='hs-varid'>b</span> <span class='hs-keyglyph'>|</span> <span class='hs-varid'>lengthRL</span> <span class='hs-varid'>a</span> <span class='hs-varop'>/=</span> <span class='hs-varid'>lengthRL</span> <span class='hs-varid'>b</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>NotEq</span>
<a name="line-231"></a> <span class='hs-keyglyph'>|</span> <span class='hs-varid'>otherwise</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>cmpSameLength</span> <span class='hs-varid'>a</span> <span class='hs-varid'>b</span>
<a name="line-232"></a> <span class='hs-keyword'>where</span> <span class='hs-varid'>cmpSameLength</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>RL</span> <span class='hs-varid'>p</span> <span class='hs-conid'>C</span><span class='hs-layout'>(</span><span class='hs-varid'>x</span> <span class='hs-varid'>y</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>RL</span> <span class='hs-varid'>p</span> <span class='hs-conid'>C</span><span class='hs-layout'>(</span><span class='hs-varid'>w</span> <span class='hs-varid'>y</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>EqCheck</span> <span class='hs-conid'>C</span><span class='hs-layout'>(</span><span class='hs-varid'>x</span> <span class='hs-varid'>w</span><span class='hs-layout'>)</span>
<a name="line-233"></a> <span class='hs-varid'>cmpSameLength</span> <span class='hs-layout'>(</span><span class='hs-varid'>x</span><span class='hs-conop'>:<:</span><span class='hs-varid'>xs</span><span class='hs-layout'>)</span> <span class='hs-varid'>xys</span> <span class='hs-keyglyph'>|</span> <span class='hs-conid'>Just</span> <span class='hs-varid'>ys</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>removeRL</span> <span class='hs-varid'>x</span> <span class='hs-varid'>xys</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>cmpSameLength</span> <span class='hs-varid'>xs</span> <span class='hs-varid'>ys</span>
<a name="line-234"></a> <span class='hs-varid'>cmpSameLength</span> <span class='hs-conid'>NilRL</span> <span class='hs-conid'>NilRL</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>IsEq</span>
<a name="line-235"></a> <span class='hs-varid'>cmpSameLength</span> <span class='hs-keyword'>_</span> <span class='hs-keyword'>_</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>NotEq</span>
<a name="line-236"></a> <span class='hs-varid'>xs</span> <span class='hs-varop'>=\/=</span> <span class='hs-varid'>ys</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>reverseRL</span> <span class='hs-varid'>xs</span> <span class='hs-varop'>=\/=</span> <span class='hs-varid'>reverseRL</span> <span class='hs-varid'>ys</span>
<a name="line-237"></a>
<a name="line-238"></a><a name="instance%20Invert%20(RL%20p)"></a><span class='hs-keyword'>instance</span> <span class='hs-layout'>(</span><span class='hs-conid'>Commute</span> <span class='hs-varid'>p</span><span class='hs-layout'>,</span> <span class='hs-conid'>Invert</span> <span class='hs-varid'>p</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=></span> <span class='hs-conid'>Invert</span> <span class='hs-layout'>(</span><span class='hs-conid'>RL</span> <span class='hs-varid'>p</span><span class='hs-layout'>)</span> <span class='hs-keyword'>where</span>
<a name="line-239"></a> <span class='hs-varid'>invert</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>reverseFL</span> <span class='hs-varop'>.</span> <span class='hs-varid'>invertRL</span>
<a name="line-240"></a>
<a name="line-241"></a><a name="CommuteFn"></a><span class='hs-comment'>-- |CommuteFn is the basis of a general framework for building up commutation</span>
<a name="line-242"></a><a name="CommuteFn"></a><span class='hs-comment'>-- operations between different patch types in a generic manner. Unfortunately</span>
<a name="line-243"></a><a name="CommuteFn"></a><span class='hs-comment'>-- type classes are not well suited to the problem because of the multiple possible</span>
<a name="line-244"></a><a name="CommuteFn"></a><span class='hs-comment'>-- routes by which the commuter for (FL p1, FL p2) can be built out of the</span>
<a name="line-245"></a><a name="CommuteFn"></a><span class='hs-comment'>-- commuter for (p1, p2) - and more complicated problems when we start building</span>
<a name="line-246"></a><a name="CommuteFn"></a><span class='hs-comment'>-- multiple constructors on top of each other. The type class resolution machinery</span>
<a name="line-247"></a><a name="CommuteFn"></a><span class='hs-comment'>-- really can't cope with selecting some route, because it doesn't know that all</span>
<a name="line-248"></a><a name="CommuteFn"></a><span class='hs-comment'>-- possible routes should be equivalent.</span>
<a name="line-249"></a><a name="CommuteFn"></a><span class='hs-keyword'>type</span> <span class='hs-conid'>CommuteFn</span> <span class='hs-varid'>p1</span> <span class='hs-varid'>p2</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>FORALL</span><span class='hs-layout'>(</span><span class='hs-varid'>x</span> <span class='hs-varid'>y</span><span class='hs-layout'>)</span> <span class='hs-layout'>(</span><span class='hs-varid'>p1</span> <span class='hs-conop'>:></span> <span class='hs-varid'>p2</span><span class='hs-layout'>)</span> <span class='hs-conid'>C</span><span class='hs-layout'>(</span><span class='hs-varid'>x</span> <span class='hs-varid'>y</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Maybe</span> <span class='hs-layout'>(</span><span class='hs-layout'>(</span><span class='hs-varid'>p2</span> <span class='hs-conop'>:></span> <span class='hs-varid'>p1</span><span class='hs-layout'>)</span> <span class='hs-conid'>C</span><span class='hs-layout'>(</span><span class='hs-varid'>x</span> <span class='hs-varid'>y</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span>
<a name="line-250"></a>
<a name="line-251"></a><a name="selfCommuter"></a><span class='hs-comment'>-- |Build a commuter between a patch and itself using the operation from the type class.</span>
<a name="line-252"></a><span class='hs-definition'>selfCommuter</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Commute</span> <span class='hs-varid'>p</span> <span class='hs-keyglyph'>=></span> <span class='hs-conid'>CommuteFn</span> <span class='hs-varid'>p</span> <span class='hs-varid'>p</span>
<a name="line-253"></a><span class='hs-definition'>selfCommuter</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>commute</span>
<a name="line-254"></a>
<a name="line-255"></a><a name="commuterIdRL"></a><span class='hs-definition'>commuterIdRL</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>CommuteFn</span> <span class='hs-varid'>p1</span> <span class='hs-varid'>p2</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>CommuteFn</span> <span class='hs-varid'>p1</span> <span class='hs-layout'>(</span><span class='hs-conid'>RL</span> <span class='hs-varid'>p2</span><span class='hs-layout'>)</span>
<a name="line-256"></a><span class='hs-definition'>commuterIdRL</span> <span class='hs-keyword'>_</span> <span class='hs-layout'>(</span><span class='hs-varid'>x</span> <span class='hs-conop'>:></span> <span class='hs-conid'>NilRL</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>return</span> <span class='hs-layout'>(</span><span class='hs-conid'>NilRL</span> <span class='hs-conop'>:></span> <span class='hs-varid'>x</span><span class='hs-layout'>)</span>
<a name="line-257"></a><span class='hs-definition'>commuterIdRL</span> <span class='hs-varid'>commuter</span> <span class='hs-layout'>(</span><span class='hs-varid'>x</span> <span class='hs-conop'>:></span> <span class='hs-layout'>(</span><span class='hs-varid'>y</span> <span class='hs-conop'>:<:</span> <span class='hs-varid'>ys</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span>
<a name="line-258"></a> <span class='hs-keyglyph'>=</span> <span class='hs-keyword'>do</span> <span class='hs-varid'>ys'</span> <span class='hs-conop'>:></span> <span class='hs-varid'>x'</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>commuterIdRL</span> <span class='hs-varid'>commuter</span> <span class='hs-layout'>(</span><span class='hs-varid'>x</span> <span class='hs-conop'>:></span> <span class='hs-varid'>ys</span><span class='hs-layout'>)</span>
<a name="line-259"></a> <span class='hs-varid'>y'</span> <span class='hs-conop'>:></span> <span class='hs-varid'>x''</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>commuter</span> <span class='hs-layout'>(</span><span class='hs-varid'>x'</span> <span class='hs-conop'>:></span> <span class='hs-varid'>y</span><span class='hs-layout'>)</span>
<a name="line-260"></a> <span class='hs-varid'>return</span> <span class='hs-layout'>(</span><span class='hs-layout'>(</span><span class='hs-varid'>y'</span> <span class='hs-conop'>:<:</span> <span class='hs-varid'>ys'</span><span class='hs-layout'>)</span> <span class='hs-conop'>:></span> <span class='hs-varid'>x''</span><span class='hs-layout'>)</span>
<a name="line-261"></a>
<a name="line-262"></a><a name="commuterIdFL"></a><span class='hs-definition'>commuterIdFL</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>CommuteFn</span> <span class='hs-varid'>p1</span> <span class='hs-varid'>p2</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>CommuteFn</span> <span class='hs-varid'>p1</span> <span class='hs-layout'>(</span><span class='hs-conid'>FL</span> <span class='hs-varid'>p2</span><span class='hs-layout'>)</span>
<a name="line-263"></a><span class='hs-definition'>commuterIdFL</span> <span class='hs-keyword'>_</span> <span class='hs-layout'>(</span><span class='hs-varid'>x</span> <span class='hs-conop'>:></span> <span class='hs-conid'>NilFL</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>return</span> <span class='hs-layout'>(</span><span class='hs-conid'>NilFL</span> <span class='hs-conop'>:></span> <span class='hs-varid'>x</span><span class='hs-layout'>)</span>
<a name="line-264"></a><span class='hs-definition'>commuterIdFL</span> <span class='hs-varid'>commuter</span> <span class='hs-layout'>(</span><span class='hs-varid'>x</span> <span class='hs-conop'>:></span> <span class='hs-layout'>(</span><span class='hs-varid'>y</span> <span class='hs-conop'>:>:</span> <span class='hs-varid'>ys</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span>
<a name="line-265"></a> <span class='hs-keyglyph'>=</span> <span class='hs-keyword'>do</span> <span class='hs-varid'>y'</span> <span class='hs-conop'>:></span> <span class='hs-varid'>x'</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>commuter</span> <span class='hs-layout'>(</span><span class='hs-varid'>x</span> <span class='hs-conop'>:></span> <span class='hs-varid'>y</span><span class='hs-layout'>)</span>
<a name="line-266"></a> <span class='hs-varid'>ys'</span> <span class='hs-conop'>:></span> <span class='hs-varid'>x''</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>commuterIdFL</span> <span class='hs-varid'>commuter</span> <span class='hs-layout'>(</span><span class='hs-varid'>x'</span> <span class='hs-conop'>:></span> <span class='hs-varid'>ys</span><span class='hs-layout'>)</span>
<a name="line-267"></a> <span class='hs-varid'>return</span> <span class='hs-layout'>(</span><span class='hs-layout'>(</span><span class='hs-varid'>y'</span> <span class='hs-conop'>:>:</span> <span class='hs-varid'>ys'</span><span class='hs-layout'>)</span> <span class='hs-conop'>:></span> <span class='hs-varid'>x''</span><span class='hs-layout'>)</span>
<a name="line-268"></a>
<a name="line-269"></a><a name="commuterFLId"></a><span class='hs-definition'>commuterFLId</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>CommuteFn</span> <span class='hs-varid'>p1</span> <span class='hs-varid'>p2</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>CommuteFn</span> <span class='hs-layout'>(</span><span class='hs-conid'>FL</span> <span class='hs-varid'>p1</span><span class='hs-layout'>)</span> <span class='hs-varid'>p2</span>
<a name="line-270"></a><span class='hs-definition'>commuterFLId</span> <span class='hs-keyword'>_</span> <span class='hs-layout'>(</span><span class='hs-conid'>NilFL</span> <span class='hs-conop'>:></span> <span class='hs-varid'>y</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>return</span> <span class='hs-layout'>(</span><span class='hs-varid'>y</span> <span class='hs-conop'>:></span> <span class='hs-conid'>NilFL</span><span class='hs-layout'>)</span>
<a name="line-271"></a><span class='hs-definition'>commuterFLId</span> <span class='hs-varid'>commuter</span> <span class='hs-layout'>(</span><span class='hs-layout'>(</span><span class='hs-varid'>x</span> <span class='hs-conop'>:>:</span> <span class='hs-varid'>xs</span><span class='hs-layout'>)</span> <span class='hs-conop'>:></span> <span class='hs-varid'>y</span><span class='hs-layout'>)</span>
<a name="line-272"></a> <span class='hs-keyglyph'>=</span> <span class='hs-keyword'>do</span> <span class='hs-varid'>y'</span> <span class='hs-conop'>:></span> <span class='hs-varid'>xs'</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>commuterFLId</span> <span class='hs-varid'>commuter</span> <span class='hs-layout'>(</span><span class='hs-varid'>xs</span> <span class='hs-conop'>:></span> <span class='hs-varid'>y</span><span class='hs-layout'>)</span>
<a name="line-273"></a> <span class='hs-varid'>y''</span> <span class='hs-conop'>:></span> <span class='hs-varid'>x'</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>commuter</span> <span class='hs-layout'>(</span><span class='hs-varid'>x</span> <span class='hs-conop'>:></span> <span class='hs-varid'>y'</span><span class='hs-layout'>)</span>
<a name="line-274"></a> <span class='hs-varid'>return</span> <span class='hs-layout'>(</span><span class='hs-varid'>y''</span> <span class='hs-conop'>:></span> <span class='hs-layout'>(</span><span class='hs-varid'>x'</span> <span class='hs-conop'>:>:</span> <span class='hs-varid'>xs'</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span>
<a name="line-275"></a>
<a name="line-276"></a><a name="partitionConflictingFL"></a><span class='hs-comment'>-- |Partition a list into the patches that commute with the given patch and those that don't (including dependencies)</span>
<a name="line-277"></a><span class='hs-definition'>partitionConflictingFL</span> <span class='hs-keyglyph'>::</span> <span class='hs-layout'>(</span><span class='hs-conid'>Commute</span> <span class='hs-varid'>p1</span><span class='hs-layout'>,</span> <span class='hs-conid'>Invert</span> <span class='hs-varid'>p1</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=></span> <span class='hs-conid'>CommuteFn</span> <span class='hs-varid'>p1</span> <span class='hs-varid'>p2</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>FL</span> <span class='hs-varid'>p1</span> <span class='hs-conid'>C</span><span class='hs-layout'>(</span><span class='hs-varid'>x</span> <span class='hs-varid'>y</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>p2</span> <span class='hs-conid'>C</span><span class='hs-layout'>(</span><span class='hs-varid'>x</span> <span class='hs-varid'>z</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>-></span> <span class='hs-layout'>(</span><span class='hs-conid'>FL</span> <span class='hs-varid'>p1</span> <span class='hs-conop'>:></span> <span class='hs-conid'>FL</span> <span class='hs-varid'>p1</span><span class='hs-layout'>)</span> <span class='hs-conid'>C</span><span class='hs-layout'>(</span><span class='hs-varid'>x</span> <span class='hs-varid'>y</span><span class='hs-layout'>)</span>
<a name="line-278"></a><span class='hs-definition'>partitionConflictingFL</span> <span class='hs-keyword'>_</span> <span class='hs-conid'>NilFL</span> <span class='hs-keyword'>_</span> <span class='hs-keyglyph'>=</span> <span class='hs-layout'>(</span><span class='hs-conid'>NilFL</span> <span class='hs-conop'>:></span> <span class='hs-conid'>NilFL</span><span class='hs-layout'>)</span>
<a name="line-279"></a><span class='hs-definition'>partitionConflictingFL</span> <span class='hs-varid'>commuter</span> <span class='hs-layout'>(</span><span class='hs-varid'>x</span> <span class='hs-conop'>:>:</span> <span class='hs-varid'>xs</span><span class='hs-layout'>)</span> <span class='hs-varid'>y</span> <span class='hs-keyglyph'>=</span>
<a name="line-280"></a> <span class='hs-keyword'>case</span> <span class='hs-varid'>commuter</span> <span class='hs-layout'>(</span><span class='hs-varid'>invert</span> <span class='hs-varid'>x</span> <span class='hs-conop'>:></span> <span class='hs-varid'>y</span><span class='hs-layout'>)</span> <span class='hs-keyword'>of</span>
<a name="line-281"></a> <span class='hs-conid'>Nothing</span> <span class='hs-keyglyph'>-></span> <span class='hs-keyword'>case</span> <span class='hs-varid'>commuteWhatWeCanFL</span> <span class='hs-layout'>(</span><span class='hs-varid'>x</span> <span class='hs-conop'>:></span> <span class='hs-varid'>xs</span><span class='hs-layout'>)</span> <span class='hs-keyword'>of</span>
<a name="line-282"></a> <span class='hs-varid'>xs_ok</span> <span class='hs-conop'>:></span> <span class='hs-varid'>x'</span> <span class='hs-conop'>:></span> <span class='hs-varid'>xs_deps</span> <span class='hs-keyglyph'>-></span>
<a name="line-283"></a> <span class='hs-keyword'>case</span> <span class='hs-varid'>partitionConflictingFL</span> <span class='hs-varid'>commuter</span> <span class='hs-varid'>xs_ok</span> <span class='hs-varid'>y</span> <span class='hs-keyword'>of</span>
<a name="line-284"></a> <span class='hs-varid'>xs_clean</span> <span class='hs-conop'>:></span> <span class='hs-varid'>xs_conflicts</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>xs_clean</span> <span class='hs-conop'>:></span> <span class='hs-layout'>(</span><span class='hs-varid'>xs_conflicts</span> <span class='hs-varop'>+>+</span> <span class='hs-layout'>(</span><span class='hs-varid'>x'</span> <span class='hs-conop'>:>:</span> <span class='hs-varid'>xs_deps</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span>
<a name="line-285"></a> <span class='hs-conid'>Just</span> <span class='hs-layout'>(</span><span class='hs-varid'>y'</span> <span class='hs-conop'>:></span> <span class='hs-keyword'>_</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>-></span>
<a name="line-286"></a> <span class='hs-keyword'>case</span> <span class='hs-varid'>partitionConflictingFL</span> <span class='hs-varid'>commuter</span> <span class='hs-varid'>xs</span> <span class='hs-varid'>y'</span> <span class='hs-keyword'>of</span>
<a name="line-287"></a> <span class='hs-varid'>xs_clean</span> <span class='hs-conop'>:></span> <span class='hs-varid'>xs_conflicts</span> <span class='hs-keyglyph'>-></span> <span class='hs-layout'>(</span><span class='hs-varid'>x</span> <span class='hs-conop'>:>:</span> <span class='hs-varid'>xs_clean</span><span class='hs-layout'>)</span> <span class='hs-conop'>:></span> <span class='hs-varid'>xs_conflicts</span>
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