Import Upstream version 20180207
[hcoop/debian/mlton.git] / doc / guide / localhost / ImplementSuffix
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22<a href="./Home">MLton 20180207</a>\r
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25<div id="header">\r
26<h1>ImplementSuffix</h1>\r
27</div>\r
28<div id="content">\r
29<div id="preamble">\r
30<div class="sectionbody">\r
31<div class="paragraph"><p><a href="ImplementSuffix">ImplementSuffix</a> is a pass for the <a href="SXML">SXML</a>\r
32<a href="IntermediateLanguage">IntermediateLanguage</a>, invoked from <a href="SXMLSimplify">SXMLSimplify</a>.</p></div>\r
33</div>\r
34</div>\r
35<div class="sect1">\r
36<h2 id="_description">Description</h2>\r
37<div class="sectionbody">\r
38<div class="paragraph"><p>This pass implements the <span class="monospaced">TopLevel_setSuffix</span> primitive, which\r
39installs a function to exit the program.</p></div>\r
40</div>\r
41</div>\r
42<div class="sect1">\r
43<h2 id="_implementation">Implementation</h2>\r
44<div class="sectionbody">\r
45<div class="ulist"><ul>\r
46<li>\r
47<p>\r
48<a href="https://github.com/MLton/mlton/blob/master/mlton/xml/implement-suffix.fun"><span class="monospaced">implement-suffix.fun</span></a>\r
49</p>\r
50</li>\r
51</ul></div>\r
52</div>\r
53</div>\r
54<div class="sect1">\r
55<h2 id="_details_and_notes">Details and Notes</h2>\r
56<div class="sectionbody">\r
57<div class="paragraph"><p><a href="ImplementSuffix">ImplementSuffix</a> works by introducing a new <span class="monospaced">ref</span> cell to contain\r
58the function of type <span class="monospaced">unit -&gt; unit</span> that should be called on program\r
59exit.</p></div>\r
60<div class="ulist"><ul>\r
61<li>\r
62<p>\r
63The following code (appropriately alpha-converted) is appended to the beginning of the <a href="SXML">SXML</a> program:\r
64</p>\r
65<div class="listingblock">\r
66<div class="content"><div class="highlight"><pre><span class="k">val</span><span class="w"> </span><span class="n">z_0</span><span class="w"> </span><span class="p">=</span><span class="w"></span>\r
67<span class="w"> </span><span class="k">fn</span><span class="w"> </span><span class="n">a_0</span><span class="w"> </span><span class="p">=&gt;</span><span class="w"></span>\r
68<span class="w"> </span><span class="k">let</span><span class="w"></span>\r
69<span class="w"> </span><span class="k">val</span><span class="w"> </span><span class="n">x_0</span><span class="w"> </span><span class="p">=</span><span class="w"></span>\r
70<span class="w"> </span><span class="s">&quot;toplevel suffix not installed&quot;</span><span class="w"></span>\r
71<span class="w"> </span><span class="k">val</span><span class="w"> </span><span class="n">x_1</span><span class="w"> </span><span class="p">=</span><span class="w"></span>\r
72<span class="w"> </span><span class="n">MLton_bug</span><span class="w"> </span><span class="p">(</span><span class="n">x_0</span><span class="p">)</span><span class="w"></span>\r
73<span class="w"> </span><span class="k">in</span><span class="w"></span>\r
74<span class="w"> </span><span class="n">x_1</span><span class="w"></span>\r
75<span class="w"> </span><span class="k">end</span><span class="w"></span>\r
76<span class="k">val</span><span class="w"> </span><span class="n">topLevelSuffixCell</span><span class="w"> </span><span class="p">=</span><span class="w"></span>\r
77<span class="w"> </span><span class="n">Ref_ref</span><span class="w"> </span><span class="p">(</span><span class="n">z_0</span><span class="p">)</span><span class="w"></span>\r
78</pre></div></div></div>\r
79</li>\r
80<li>\r
81<p>\r
82Any occurrence of\r
83</p>\r
84<div class="listingblock">\r
85<div class="content"><div class="highlight"><pre><span class="k">val</span><span class="w"> </span><span class="n">x_0</span><span class="w"> </span><span class="p">=</span><span class="w"></span>\r
86<span class="w"> </span><span class="n">TopLevel_setSuffix</span><span class="w"> </span><span class="p">(</span><span class="n">f_0</span><span class="p">)</span><span class="w"></span>\r
87</pre></div></div></div>\r
88<div class="paragraph"><p>is rewritten to</p></div>\r
89<div class="listingblock">\r
90<div class="content"><div class="highlight"><pre><span class="k">val</span><span class="w"> </span><span class="n">x_0</span><span class="w"> </span><span class="p">=</span><span class="w"></span>\r
91<span class="w"> </span><span class="n">Ref_assign</span><span class="w"> </span><span class="p">(</span><span class="n">topLevelSuffixCell</span><span class="p">,</span><span class="w"> </span><span class="n">f_0</span><span class="p">)</span><span class="w"></span>\r
92</pre></div></div></div>\r
93</li>\r
94<li>\r
95<p>\r
96The following code (appropriately alpha-converted) is appended to the end of the <a href="SXML">SXML</a> program:\r
97</p>\r
98<div class="listingblock">\r
99<div class="content"><div class="highlight"><pre><span class="k">val</span><span class="w"> </span><span class="n">f_0</span><span class="w"> </span><span class="p">=</span><span class="w"></span>\r
100<span class="w"> </span><span class="n">Ref_deref</span><span class="w"> </span><span class="p">(</span><span class="n">topLevelSuffixCell</span><span class="p">)</span><span class="w"></span>\r
101<span class="k">val</span><span class="w"> </span><span class="n">z_0</span><span class="w"> </span><span class="p">=</span><span class="w"></span>\r
102<span class="w"> </span><span class="p">()</span><span class="w"></span>\r
103<span class="k">val</span><span class="w"> </span><span class="n">x_0</span><span class="w"> </span><span class="p">=</span><span class="w"></span>\r
104<span class="w"> </span><span class="n">f_0</span><span class="w"> </span><span class="n">z_0</span><span class="w"></span>\r
105</pre></div></div></div>\r
106</li>\r
107</ul></div>\r
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