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<a href='https://github.com/akkartik/mu/blob/main/linux/406int32.mu'>https://github.com/akkartik/mu/blob/main/linux/406int32.mu</a>
<pre id='vimCodeElement'>
<span id="L1" class="LineNr"> 1 </span><span class="muComment"># Some slow but convenient helpers</span>
<span id="L2" class="LineNr"> 2 </span>
<span id="L3" class="LineNr"> 3 </span><span class="muComment"># slow, iterative shift-left instruction</span>
<span id="L4" class="LineNr"> 4 </span><span class="muComment"># preconditions: _nr &gt;= 0, _dr &gt; 0</span>
<span id="L5" class="LineNr"> 5 </span><span class="PreProc">fn</span> <span class="muFunction"><a href='406int32.mu.html#L5'>repeated-shift-left</a></span> nr: int, dr: int<span class="PreProc"> -&gt; </span>_/eax: int <span class="Delimiter">{</span>
<span id="L6" class="LineNr"> 6 </span>  <span class="PreProc">var</span> result/eax: int <span class="Special">&lt;-</span> copy nr
<span id="L7" class="LineNr"> 7 </span>  <span class="Delimiter">{</span>
<span id="L8" class="LineNr"> 8 </span>    compare dr, <span class="Constant">0</span>
<span id="L9" class="LineNr"> 9 </span>    <span class="PreProc">break-if-&lt;=</span>
<span id="L10" class="LineNr">10 </span>    result <span class="Special">&lt;-</span> shift-left <span class="Constant">1</span>
<span id="L11" class="LineNr">11 </span>    decrement dr
<span id="L12" class="LineNr">12 </span>    <span class="PreProc">loop</span>
<span id="L13" class="LineNr">13 </span>  <span class="Delimiter">}</span>
<span id="L14" class="LineNr">14 </span>  <span class="PreProc">return</span> result
<span id="L15" class="LineNr">15 </span><span class="Delimiter">}</span>
<span id="L16" class="LineNr">16 </span>
<span id="L17" class="LineNr">17 </span><span class="muComment"># slow, iterative shift-right instruction</span>
<span id="L18" class="LineNr">18 </span><span class="muComment"># preconditions: _nr &gt;= 0, _dr &gt; 0</span>
<span id="L19" class="LineNr">19 </span><span class="PreProc">fn</span> <span class="muFunction"><a href='406int32.mu.html#L19'>repeated-shift-right</a></span> nr: int, dr: int<span class="PreProc"> -&gt; </span>_/eax: int <span class="Delimiter">{</span>
<span id="L20" class="LineNr">20 </span>  <span class="PreProc">var</span> result/eax: int <span class="Special">&lt;-</span> copy nr
<span id="L21" class="LineNr">21 </span>  <span class="Delimiter">{</span>
<span id="L22" class="LineNr">22 </span>    compare dr
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<pre id='vimCodeElement'>
<span class="Comment">//: Exclusive containers contain exactly one of a fixed number of 'variants'</span>
<span class="Comment">//: of different types.</span>
<span class="Comment">//:</span>
<span class="Comment">//: They also implicitly contain a tag describing precisely which variant is</span>
<span class="Comment">//: currently stored in them.</span>

<span class="Delimiter">:(before &quot;End Mu Types Initialization&quot;)</span>
<span class="Comment">//: We'll use this container as a running example, with two number elements.</span>
<span class="Delimiter">{</span>
type_ordinal tmp = Type_ordinal[<span class="Constant">&quot;number-or-point&quot;</span>] = Next_type_ordinal++<span class="Delimiter">;</span>
Type[tmp]<span class="Delimiter">.</span>size = <span class="Constant">2</span><span class="Delimiter">;</span>
Type[tmp]<span class="Delimiter">.</span>kind = exclusive_container<span class="Delimiter">;</span>
Type[tmp]<span class="Delimiter">.</span>name = <span class="Constant">&quot;number-or-point&quot;</span><span class="Delimiter">;</span>
vector&lt;type_ordinal&gt; t1<span class="Delimiter">;</span>
t1<span class="Delimiter">.</span>push_back<span class="Delimiter">(</span>number<span class="Delimiter">);</span>
Type[tmp]<span class="Delimiter">.</span>elements<span class="Delimiter">.</span>push_back<span class="Delimiter">(</span>t1<span class="Delimiter">);</span>
vector&lt;type_ordinal&gt; t2<span class="Delimiter">;</span>
t2<span class="Delimiter">.</span>push_back<span class="Delimiter">(</span>point<span class="Delimiter">);</span>
Type[tmp]<span class="Delimiter">.</span>elements<span class="Delimiter">.</span>push_back<span class="Delimiter">(</span>t2<span class="Delimiter">);</span>
Type[tmp]<span class="Delimiter">.</span>element_names<span class="Delimiter">.</span>push_back<span class="Delimiter">(</span><span class="Constant">&quot;i&quot;</span><span class="Delimiter">);</span>
Type[tmp]<span class="Delimiter">.</span>element_names<span class="Delimiter">.</span>push_back<span class="Delimiter">(</span><span class="Constant">&quot;p&quot;</span><span class="Delimiter">);</span>
<span class="Delimiter">}</span>

<span class="Comment">//: Tests in this layer often explicitly setup memory before reading it as an</span>
<span class="Comment">//: array. Don't do this in general. I'm tagging exceptions with /raw to</span>
<span class="Comment">//: avoid warnings.</span>
<span class="Delimiter">:(scenario copy_exclusive_container)</span>
<span class="Comment"># Copying exclusive containers copies all their contents and an extra location for the tag.</span>
recipe main [
  <span class="Constant">1</span>:number<span class="Special"> &lt;- </span>copy <span class="Constant">1</span>  <span class="Comment"># 'point' variant</span>
  <span class="Constant">2</span>:number<span class="Special"> &lt;- </span>copy <span class="Constant">34</span>
  <span class="Constant">3</span>:number<span class="Special"> &lt;- </span>copy <span class="Constant">35</span>
  <span class="Constant">4</span>:number-or-point<span class="Special"> &lt;- </span>copy <span class="Constant">1</span>:number-or-point/<span class="Special">raw</span>  <span class="Comment"># unsafe</span>
]
<span class="traceContains">+mem: storing 1 in location 4</span>
<span class="traceContains">+mem: storing 34 in location 5</span>
<span class="traceContains">+mem: storing 35 in location 6</span>

<span class="Delimiter">:(before &quot;End size_of(types) Cases&quot;)</span>
if <span class="Delimiter">(</span>t<span class="Delimiter">.</span>kind == exclusive_container<span class="Delimiter">)</span> <span class="Delimiter">{</span>
  <span class="Comment">// size of an exclusive container is the size of its largest variant</span>
  <span class="Comment">// (So like containers, it can't contain arrays.)</span>
  long long int result = <span class="Constant">0</span><span class="Delimiter">;</span>
  for <span class="Delimiter">(</span>long long int i = <span class="Constant">0</span><span class="Delimiter">;</span> i &lt; t<span class="Delimiter">.</span>size<span class="Delimiter">;</span> ++i<span class="Delimiter">)</span> <span class="Delimiter">{</span>
    long long int tmp = size_of<span class="Delimiter">(</span>t<span class="Delimiter">.</span>elements<span class="Delimiter">.</span>at<span class="Delimiter">(</span>i<span class="Delimiter">));</span>
    if <span class="Delimiter">(</span>tmp &gt; result<span class="Delimiter">)</span> result = tmp<span class="Delimiter">;</span>
  <span class="Delimiter">}</span>
  <span class="Comment">// ...+1 for its tag.</span>
  <span class="Identifier">return</span> result+<span class="Constant">1</span><span class="Delimiter">;</span>
<span class="Delimiter">}</span>

<span class="SalientComment">//:: To access variants of an exclusive container, use 'maybe-convert'.</span>
<span class="Comment">//: It always returns an address (so that you can modify it) or null (to</span>
<span class="Comment">//: signal that the conversion failed (because the container contains a</span>
<span class="Comment">//: different variant).</span>

<span class="Comment">//: 'maybe-convert' requires a literal in ingredient 1. We'll use a synonym</span>
<span class="Comment">//: called 'variant'.</span>
<span class="Delimiter">:(before &quot;End Mu Types Initialization&quot;)</span>
Type_ordinal[<span class="Constant">&quot;variant&quot;</span>] = <span class="Constant">0</span><span class="Delimiter">;</span>

<span class="Delimiter">:(scenario maybe_convert)</span>
recipe main [
  <span class="Constant">12</span>:number<span class="Special"> &lt;- </span>copy <span class="Constant">1</span>
  <span class="Constant">13</span>:number<span class="Special"> &lt;- </span>copy <span class="Constant">35</span>
  <span class="Constant">14</span>:number<span class="Special"> &lt;- </span>copy <span class="Constant">36</span>
  <span class="Constant">20</span>:address:point<span class="Special"> &lt;- </span>maybe-convert <span class="Constant">12</span>:number-or-point/<span class="Special">raw</span><span class="Delimiter">,</span> <span class="Constant">1</span>:variant  <span class="Comment"># unsafe</span>
]
<span class="traceContains">+mem: storing 13 in location 20</span>

<span class="Delimiter">:(scenario maybe_convert_fail)</span>
recipe main [
  <span class="Constant">12</span>:number<span class="Special"> &lt;- </span>copy <span class="Constant">1</span>
  <span class="Constant">13</span>:number<span class="Special"> &lt;- </span>copy <span class="Constant">35</span>
  <span class="Constant">14</span>:number<span class="Special"> &lt;- </span>copy <span class="Constant">36</span>
  <span class="Constant">20</span>:address:point<span class="Special"> &lt;- </span>maybe-convert <span class="Constant">12</span>:number-or-point/<span class="Special">raw</span><span class="Delimiter">,</span> <span class="Constant">0</span>:variant  <span class="Comment"># unsafe</span>
]
<span class="traceContains">+mem: storing 0 in location 20</span>

<span class="Delimiter">:(before &quot;End Primitive Recipe Declarations&quot;)</span>
MAYBE_CONVERT<span class="Delimiter">,</span>
<span class="Delimiter">:(before &quot;End Primitive Recipe Numbers&quot;)</span>
Recipe_ordinal[<span class="Constant">&quot;maybe-convert&quot;</span>] = MAYBE_CONVERT<span class="Delimiter">;</span>
<span class="Delimiter">:(before &quot;End Primitive Recipe Implementations&quot;)</span>
case MAYBE_CONVERT: <span class="Delimiter">{</span>
  if <span class="Delimiter">(</span>SIZE<span class="Delimiter">(</span>ingredients<span class="Delimiter">)</span> != <span class="Constant">2</span><span class="Delimiter">)</span> <span class="Delimiter">{</span>
    raise &lt;&lt; current_recipe_name<span class="Delimiter">()</span> &lt;&lt; <span class="Constant">&quot;: 'maybe-convert' expects exactly 2 ingredients in '&quot;</span> &lt;&lt; current_instruction<span class="Delimiter">().</span>to_string<span class="Delimiter">()</span> &lt;&lt; <span class="Constant">&quot;'</span><span class="cSpecial">\n</span><span class="Constant">&quot;</span> &lt;&lt; end<span class="Delimiter">();</span>
    <span class="Identifier">break</span><span class="Delimiter">;</span>
  <span class="Delimiter">}</span>
  reagent base = canonize<span class="Delimiter">(</span>current_instruction<span class="Delimiter">().</span>ingredients<span class="Delimiter">.</span>at<span class="Delimiter">(</span><span class="Constant">0</span><span class="Delimiter">));</span>
  long long int base_address = base<span class="Delimiter">.</span>value<span class="Delimiter">;</span>
  if <span class="Delimiter">(</span>base_address == <span class="Constant">0</span><span class="Delimiter">)</span> <span class="Delimiter">{</span>
    raise &lt;&lt; current_recipe_name<span class="Delimiter">()</span> &lt;&lt; <span class="Constant">&quot;: tried to access location 0 in '&quot;</span> &lt;&lt; current_instruction<span class="Delimiter">().</span>to_string<span class="Delimiter">()</span> &lt;&lt; <span class="Constant">&quot;'</span><span class="cSpecial">\n</span><span class="Constant">&quot;</span> &lt;&lt; end<span class="Delimiter">();</span>
    <span class="Identifier">break</span><span class="Delimiter">;</span>
  <span class="Delimiter">}</span>
  if <span class="Delimiter">(</span>base<span class="Delimiter">.</span>types<span class="Delimiter">.</span>empty<span class="Delimiter">()</span> || Type[base<span class="Delimiter">.</span>types<span class="Delimiter">.</span>at<span class="Delimiter">(</span><span class="Constant">0</span><span class="Delimiter">)</span>]<span class="Delimiter">.</span>kind != exclusive_container<span class="Delimiter">)</span> <span class="Delimiter">{</span>
    raise &lt;&lt; current_recipe_name <span class="Delimiter">()</span> &lt;&lt; <span class="Constant">&quot;: first ingredient of 'maybe-convert' should be an exclusive-container, but got &quot;</span> &lt;&lt; base<span class="Delimiter">.</span>original_string &lt;&lt; <span class="cSpecial">'\n'</span> &lt;&lt; end<span class="Delimiter">();</span>
    <span class="Identifier">break</span><span class="Delimiter">;</span>
  <span class="Delimiter">}</span>
  if <span class="Delimiter">(</span>!is_literal<span class="Delimiter">(</span>current_instruction<span class="Delimiter">().</span>ingredients<span class="Delimiter">.</span>at<span class="Delimiter">(</span><span class="Constant">1</span><span class="Delimiter">)))</span> <span class="Delimiter">{</span>
    raise &lt;&lt; current_recipe_name<span class="Delimiter">()</span> &lt;&lt; <span class="Constant">&quot;: second ingredient of 'maybe-convert' should have type 'variant', but got &quot;</span> &lt;&lt; current_instruction<span class="Delimiter">().</span>ingredients<span class="Delimiter">.</span>at<span class="Delimiter">(</span><span class="Constant">1</span><span class="Delimiter">).</span>original_string &lt;&lt; <span class="cSpecial">'\n'</span> &lt;&lt; end<span class="Delimiter">();</span>
    <span class="Identifier">break</span><span class="Delimiter">;</span>
  <span class="Delimiter">}</span>
  long long int tag = current_instruction<span class="Delimiter">().</span>ingredients<span class="Delimiter">.</span>at<span class="Delimiter">(</span><span class="Constant">1</span><span class="Delimiter">).</span>value<span class="Delimiter">;</span>
  long long int result<span class="Delimiter">;</span>
  if <span class="Delimiter">(</span>tag == static_cast&lt;long long int&gt;<span class="Delimiter">(</span>Memory[base_address]<span class="Delimiter">))</span> <span class="Delimiter">{</span>
    result = base_address+<span class="Constant">1</span><span class="Delimiter">;</span>
  <span class="Delimiter">}</span>
  else <span class="Delimiter">{</span>
    result = <span class="Constant">0</span><span class="Delimiter">;</span>
  <span class="Delimiter">}</span>
  products<span class="Delimiter">.</span>resize<span class="Delimiter">(</span><span class="Constant">1</span><span class="Delimiter">);</span>
  products<span class="Delimiter">.</span>at<span class="Delimiter">(</span><span class="Constant">0</span><span class="Delimiter">).</span>push_back<span class="Delimiter">(</span>result<span class="Delimiter">);</span>
  <span class="Identifier">break</span><span class="Delimiter">;</span>
<span class="Delimiter">}</span>

<span class="SalientComment">//:: Allow exclusive containers to be defined in mu code.</span>

<span class="Delimiter">:(scenario exclusive_container)</span>
exclusive-container foo [
  x:number
  y:number
]
<span class="traceContains">+parse: reading exclusive-container foo</span>
<span class="traceContains">+parse:   element name: x</span>
<span class="traceContains">+parse:   type: 1</span>
<span class="traceContains">+parse:   element name: y</span>
<span class="traceContains">+parse:   type: 1</span>

<span class="Delimiter">:(before &quot;End Command Handlers&quot;)</span>
else if <span class="Delimiter">(</span>command == <span class="Constant">&quot;exclusive-container&quot;</span><span class="Delimiter">)</span> <span class="Delimiter">{</span>
  insert_container<span class="Delimiter">(</span>command<span class="Delimiter">,</span> exclusive_container<span class="Delimiter">,</span> in<span class="Delimiter">);</span>
<span class="Delimiter">}</span>

<span class="SalientComment">//:: To construct exclusive containers out of variant types, use 'merge'.</span>
<span class="Delimiter">:(scenario lift_to_exclusive_container)</span>
exclusive-container foo [
  x:number
  y:number
]

recipe main [
  <span class="Constant">1</span>:number<span class="Special"> &lt;- </span>copy <span class="Constant">34</span>
  <span class="Constant">2</span>:foo<span class="Special"> &lt;- </span>merge <span class="Constant">0</span>/x<span class="Delimiter">,</span> <span class="Constant">1</span>:number
  <span class="Constant">4</span>:foo<span class="Special"> &lt;- </span>merge <span class="Constant">1</span>/x<span class="Delimiter">,</span> <span class="Constant">1</span>:number
]
<span class="traceContains">+mem: storing 0 in location 2</span>
<span class="traceContains">+mem: storing 34 in location 3</span>
<span class="traceContains">+mem: storing 1 in location 4</span>
<span class="traceContains">+mem: storing 34 in location 5</span>
</pre>
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