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<title>src/full/Agda/TypeChecking/EtaContract.hs</title>
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<pre><a name="line-1"></a><span class='hs-comment'>{-# LANGUAGE CPP #-}</span>
<a name="line-2"></a>
<a name="line-3"></a><span class='hs-comment'>-- | Compute eta short normal forms.</span>
<a name="line-4"></a><span class='hs-keyword'>module</span> <span class='hs-conid'>Agda</span><span class='hs-varop'>.</span><span class='hs-conid'>TypeChecking</span><span class='hs-varop'>.</span><span class='hs-conid'>EtaContract</span> <span class='hs-keyword'>where</span>
<a name="line-5"></a>
<a name="line-6"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Agda</span><span class='hs-varop'>.</span><span class='hs-conid'>Syntax</span><span class='hs-varop'>.</span><span class='hs-conid'>Common</span>
<a name="line-7"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Agda</span><span class='hs-varop'>.</span><span class='hs-conid'>Syntax</span><span class='hs-varop'>.</span><span class='hs-conid'>Internal</span>
<a name="line-8"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Agda</span><span class='hs-varop'>.</span><span class='hs-conid'>Syntax</span><span class='hs-varop'>.</span><span class='hs-conid'>Internal</span><span class='hs-varop'>.</span><span class='hs-conid'>Generic</span>
<a name="line-9"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Agda</span><span class='hs-varop'>.</span><span class='hs-conid'>TypeChecking</span><span class='hs-varop'>.</span><span class='hs-conid'>Substitute</span>
<a name="line-10"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Agda</span><span class='hs-varop'>.</span><span class='hs-conid'>TypeChecking</span><span class='hs-varop'>.</span><span class='hs-conid'>Free</span>
<a name="line-11"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Agda</span><span class='hs-varop'>.</span><span class='hs-conid'>TypeChecking</span><span class='hs-varop'>.</span><span class='hs-conid'>Monad</span>
<a name="line-12"></a><span class='hs-keyword'>import</span> <span class='hs-comment'>{-# SOURCE #-}</span> <span class='hs-conid'>Agda</span><span class='hs-varop'>.</span><span class='hs-conid'>TypeChecking</span><span class='hs-varop'>.</span><span class='hs-conid'>Records</span>
<a name="line-13"></a><span class='hs-keyword'>import</span> <span class='hs-comment'>{-# SOURCE #-}</span> <span class='hs-conid'>Agda</span><span class='hs-varop'>.</span><span class='hs-conid'>TypeChecking</span><span class='hs-varop'>.</span><span class='hs-conid'>Datatypes</span>
<a name="line-14"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Agda</span><span class='hs-varop'>.</span><span class='hs-conid'>Utils</span><span class='hs-varop'>.</span><span class='hs-conid'>Monad</span>
<a name="line-15"></a>
<a name="line-16"></a><span class='hs-cpp'>#include "../undefined.h"</span>
<a name="line-17"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Agda</span><span class='hs-varop'>.</span><span class='hs-conid'>Utils</span><span class='hs-varop'>.</span><span class='hs-conid'>Impossible</span>
<a name="line-18"></a>
<a name="line-19"></a><a name="BinAppView"></a><span class='hs-comment'>-- TODO: move to Agda.Syntax.Internal.SomeThing</span>
<a name="line-20"></a><a name="BinAppView"></a><span class='hs-keyword'>data</span> <span class='hs-conid'>BinAppView</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>App</span> <span class='hs-conid'>Term</span> <span class='hs-layout'>(</span><span class='hs-conid'>Arg</span> <span class='hs-conid'>Term</span><span class='hs-layout'>)</span>
<a name="line-21"></a> <span class='hs-keyglyph'>|</span> <span class='hs-conid'>NoApp</span> <span class='hs-conid'>Term</span>
<a name="line-22"></a>
<a name="line-23"></a><a name="binAppView"></a><span class='hs-definition'>binAppView</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Term</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>BinAppView</span>
<a name="line-24"></a><span class='hs-definition'>binAppView</span> <span class='hs-varid'>t</span> <span class='hs-keyglyph'>=</span> <span class='hs-keyword'>case</span> <span class='hs-varid'>t</span> <span class='hs-keyword'>of</span>
<a name="line-25"></a> <span class='hs-conid'>Var</span> <span class='hs-varid'>i</span> <span class='hs-varid'>xs</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>app</span> <span class='hs-layout'>(</span><span class='hs-conid'>Var</span> <span class='hs-varid'>i</span><span class='hs-layout'>)</span> <span class='hs-varid'>xs</span>
<a name="line-26"></a> <span class='hs-conid'>Def</span> <span class='hs-varid'>c</span> <span class='hs-varid'>xs</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>app</span> <span class='hs-layout'>(</span><span class='hs-conid'>Def</span> <span class='hs-varid'>c</span><span class='hs-layout'>)</span> <span class='hs-varid'>xs</span>
<a name="line-27"></a> <span class='hs-conid'>Con</span> <span class='hs-varid'>c</span> <span class='hs-varid'>xs</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>app</span> <span class='hs-layout'>(</span><span class='hs-conid'>Con</span> <span class='hs-varid'>c</span><span class='hs-layout'>)</span> <span class='hs-varid'>xs</span>
<a name="line-28"></a> <span class='hs-conid'>Lit</span> <span class='hs-keyword'>_</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>noApp</span>
<a name="line-29"></a> <span class='hs-conid'>Level</span> <span class='hs-keyword'>_</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>noApp</span> <span class='hs-comment'>-- could be an application, but let's not eta contract levels</span>
<a name="line-30"></a> <span class='hs-conid'>Lam</span> <span class='hs-keyword'>_</span> <span class='hs-keyword'>_</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>noApp</span>
<a name="line-31"></a> <span class='hs-conid'>Pi</span> <span class='hs-keyword'>_</span> <span class='hs-keyword'>_</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>noApp</span>
<a name="line-32"></a> <span class='hs-conid'>Sort</span> <span class='hs-keyword'>_</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>noApp</span>
<a name="line-33"></a> <span class='hs-conid'>MetaV</span> <span class='hs-keyword'>_</span> <span class='hs-keyword'>_</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>noApp</span>
<a name="line-34"></a> <span class='hs-conid'>DontCare</span> <span class='hs-keyword'>_</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>noApp</span>
<a name="line-35"></a> <span class='hs-conid'>Shared</span> <span class='hs-varid'>p</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>binAppView</span> <span class='hs-layout'>(</span><span class='hs-varid'>derefPtr</span> <span class='hs-varid'>p</span><span class='hs-layout'>)</span> <span class='hs-comment'>-- destroys sharing</span>
<a name="line-36"></a> <span class='hs-keyword'>where</span>
<a name="line-37"></a> <span class='hs-varid'>noApp</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>NoApp</span> <span class='hs-varid'>t</span>
<a name="line-38"></a> <span class='hs-varid'>app</span> <span class='hs-varid'>f</span> <span class='hs-conid'>[]</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>noApp</span>
<a name="line-39"></a> <span class='hs-varid'>app</span> <span class='hs-varid'>f</span> <span class='hs-varid'>xs</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>App</span> <span class='hs-layout'>(</span><span class='hs-varid'>f</span> <span class='hs-varop'>$</span> <span class='hs-varid'>init</span> <span class='hs-varid'>xs</span><span class='hs-layout'>)</span> <span class='hs-layout'>(</span><span class='hs-varid'>last</span> <span class='hs-varid'>xs</span><span class='hs-layout'>)</span>
<a name="line-40"></a>
<a name="line-41"></a><a name="etaContract"></a><span class='hs-definition'>etaContract</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>TermLike</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>=></span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>TCM</span> <span class='hs-varid'>a</span>
<a name="line-42"></a><span class='hs-definition'>etaContract</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>traverseTermM</span> <span class='hs-varid'>etaOnce</span>
<a name="line-43"></a>
<a name="line-44"></a><a name="etaOnce"></a><span class='hs-definition'>etaOnce</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Term</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>TCM</span> <span class='hs-conid'>Term</span>
<a name="line-45"></a><span class='hs-definition'>etaOnce</span> <span class='hs-varid'>v</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>eta</span> <span class='hs-varid'>v</span>
<a name="line-46"></a> <span class='hs-keyword'>where</span>
<a name="line-47"></a> <span class='hs-varid'>eta</span> <span class='hs-varid'>v</span><span class='hs-keyglyph'>@</span><span class='hs-conid'>Shared</span><span class='hs-layout'>{</span><span class='hs-layout'>}</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>updateSharedTerm</span> <span class='hs-varid'>eta</span> <span class='hs-varid'>v</span>
<a name="line-48"></a> <span class='hs-varid'>eta</span> <span class='hs-varid'>t</span><span class='hs-keyglyph'>@</span><span class='hs-layout'>(</span><span class='hs-conid'>Lam</span> <span class='hs-varid'>h</span> <span class='hs-layout'>(</span><span class='hs-conid'>Abs</span> <span class='hs-keyword'>_</span> <span class='hs-varid'>b</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-keyword'>do</span> <span class='hs-comment'>-- NoAbs can't be eta'd</span>
<a name="line-49"></a> <span class='hs-varid'>imp</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>shouldEtaContractImplicit</span>
<a name="line-50"></a> <span class='hs-keyword'>case</span> <span class='hs-varid'>binAppView</span> <span class='hs-varid'>b</span> <span class='hs-keyword'>of</span>
<a name="line-51"></a> <span class='hs-conid'>App</span> <span class='hs-varid'>u</span> <span class='hs-layout'>(</span><span class='hs-conid'>Arg</span> <span class='hs-varid'>h'</span> <span class='hs-varid'>r</span> <span class='hs-varid'>v</span><span class='hs-layout'>)</span>
<a name="line-52"></a> <span class='hs-keyglyph'>|</span> <span class='hs-layout'>(</span><span class='hs-varid'>r</span> <span class='hs-varop'>==</span> <span class='hs-conid'>Irrelevant</span> <span class='hs-varop'>||</span> <span class='hs-varid'>isVar0</span> <span class='hs-varid'>v</span><span class='hs-layout'>)</span> <span class='hs-varop'>&&</span> <span class='hs-varid'>allowed</span> <span class='hs-varid'>imp</span> <span class='hs-varid'>h'</span> <span class='hs-varop'>&&</span> <span class='hs-varid'>not</span> <span class='hs-layout'>(</span><span class='hs-varid'>freeIn</span> <span class='hs-num'>0</span> <span class='hs-varid'>u</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>-></span>
<a name="line-53"></a> <span class='hs-varid'>return</span> <span class='hs-varop'>$</span> <span class='hs-varid'>subst</span> <span class='hs-sel'>__IMPOSSIBLE__</span> <span class='hs-varid'>u</span>
<a name="line-54"></a> <span class='hs-keyword'>_</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>return</span> <span class='hs-varid'>t</span>
<a name="line-55"></a> <span class='hs-keyword'>where</span>
<a name="line-56"></a> <span class='hs-varid'>isVar0</span> <span class='hs-layout'>(</span><span class='hs-conid'>Shared</span> <span class='hs-varid'>p</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>isVar0</span> <span class='hs-layout'>(</span><span class='hs-varid'>derefPtr</span> <span class='hs-varid'>p</span><span class='hs-layout'>)</span>
<a name="line-57"></a> <span class='hs-varid'>isVar0</span> <span class='hs-layout'>(</span><span class='hs-conid'>Var</span> <span class='hs-num'>0</span> <span class='hs-conid'>[]</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>True</span>
<a name="line-58"></a> <span class='hs-varid'>isVar0</span> <span class='hs-layout'>(</span><span class='hs-conid'>Level</span> <span class='hs-layout'>(</span><span class='hs-conid'>Max</span> <span class='hs-keyglyph'>[</span><span class='hs-conid'>Plus</span> <span class='hs-num'>0</span> <span class='hs-varid'>l</span><span class='hs-keyglyph'>]</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-keyword'>case</span> <span class='hs-varid'>l</span> <span class='hs-keyword'>of</span>
<a name="line-59"></a> <span class='hs-conid'>NeutralLevel</span> <span class='hs-varid'>v</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>isVar0</span> <span class='hs-varid'>v</span>
<a name="line-60"></a> <span class='hs-conid'>UnreducedLevel</span> <span class='hs-varid'>v</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>isVar0</span> <span class='hs-varid'>v</span>
<a name="line-61"></a> <span class='hs-conid'>BlockedLevel</span><span class='hs-layout'>{</span><span class='hs-layout'>}</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>False</span>
<a name="line-62"></a> <span class='hs-conid'>MetaLevel</span><span class='hs-layout'>{</span><span class='hs-layout'>}</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>False</span>
<a name="line-63"></a> <span class='hs-varid'>isVar0</span> <span class='hs-keyword'>_</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>False</span>
<a name="line-64"></a> <span class='hs-varid'>allowed</span> <span class='hs-varid'>imp</span> <span class='hs-varid'>h'</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>h</span> <span class='hs-varop'>==</span> <span class='hs-varid'>h'</span> <span class='hs-varop'>&&</span> <span class='hs-layout'>(</span><span class='hs-varid'>imp</span> <span class='hs-varop'>||</span> <span class='hs-varid'>h</span> <span class='hs-varop'>==</span> <span class='hs-conid'>NotHidden</span><span class='hs-layout'>)</span>
<a name="line-65"></a> <span class='hs-varid'>eta</span> <span class='hs-varid'>t</span><span class='hs-keyglyph'>@</span><span class='hs-layout'>(</span><span class='hs-conid'>Con</span> <span class='hs-varid'>c</span> <span class='hs-varid'>args</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-keyword'>do</span>
<a name="line-66"></a> <span class='hs-varid'>r</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>getConstructorData</span> <span class='hs-varid'>c</span>
<a name="line-67"></a> <span class='hs-varid'>ifM</span> <span class='hs-layout'>(</span><span class='hs-varid'>isEtaRecord</span> <span class='hs-varid'>r</span><span class='hs-layout'>)</span>
<a name="line-68"></a> <span class='hs-layout'>(</span><span class='hs-varid'>etaContractRecord</span> <span class='hs-varid'>r</span> <span class='hs-varid'>c</span> <span class='hs-varid'>args</span><span class='hs-layout'>)</span>
<a name="line-69"></a> <span class='hs-layout'>(</span><span class='hs-varid'>return</span> <span class='hs-varid'>t</span><span class='hs-layout'>)</span>
<a name="line-70"></a> <span class='hs-varid'>eta</span> <span class='hs-varid'>t</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>return</span> <span class='hs-varid'>t</span>
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