File: ShowBasis

package info (click to toggle)
mlton 20130715-3
  • links: PTS
  • area: main
  • in suites: stretch
  • size: 60,900 kB
  • ctags: 69,386
  • sloc: xml: 34,418; ansic: 17,399; lisp: 2,879; makefile: 1,605; sh: 1,254; pascal: 256; python: 143; asm: 97
file content (170 lines) | stat: -rw-r--r-- 10,375 bytes parent folder | download 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
 
<!DOCTYPE html>
<html lang="en">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<meta name="generator" content="AsciiDoc 8.6.8">
<title>ShowBasis</title>
<link rel="stylesheet" href="./asciidoc.css" type="text/css">
<link rel="stylesheet" href="./pygments.css" type="text/css">


<script type="text/javascript" src="./asciidoc.js"></script>
<script type="text/javascript">
/*<![CDATA[*/
asciidoc.install();
/*]]>*/
</script>
<link rel="stylesheet" href="./mlton.css" type="text/css"/>
</head>
<body class="article">
<div id="banner">
<div id="banner-home">
<a href="./Home">MLton 20130715</a>
</div>
</div>
<div id="header">
<h1>ShowBasis</h1>
</div>
<div id="content">
<div id="preamble">
<div class="sectionbody">
<div class="paragraph"><p>MLton has a flag, <span class="monospaced">-show-basis &lt;file&gt;</span>, that causes MLton to pretty
print to <em>file</em> the basis defined by the input program.  For example,
if <span class="monospaced">foo.sml</span> contains</p></div>
<div class="listingblock">
<div class="content"><div class="highlight"><pre><span class="k">fun</span><span class="w"> </span><span class="n">f</span><span class="w"> </span><span class="n">x</span><span class="w"> </span><span class="p">=</span><span class="w"> </span><span class="n">x</span><span class="w"> </span><span class="n">+</span><span class="w"> </span><span class="mi">1</span><span class="w"></span>
</pre></div></div></div>
<div class="paragraph"><p>then <span class="monospaced">mlton -show-basis foo.basis foo.sml</span> will create <span class="monospaced">foo.basis</span>
with the following contents.</p></div>
<div class="listingblock">
<div class="content monospaced">
<pre>val f: int -&gt; int</pre>
</div></div>
<div class="paragraph"><p>If you only want to see the basis and do not wish to compile the
program, you can call MLton with <span class="monospaced">-stop tc</span>.</p></div>
</div>
</div>
<div class="sect1">
<h2 id="_displaying_signatures">Displaying signatures</h2>
<div class="sectionbody">
<div class="paragraph"><p>When displaying signatures, MLton prefixes types defined in the
signature them with <span class="monospaced">?.</span> to distinguish them from types defined in the
environment.  For example,</p></div>
<div class="listingblock">
<div class="content"><div class="highlight"><pre><span class="k">signature</span><span class="w"> </span><span class="n">SIG</span><span class="w"> </span><span class="p">=</span><span class="w"></span>
<span class="w">   </span><span class="k">sig</span><span class="w"></span>
<span class="w">      </span><span class="k">type</span><span class="w"> </span><span class="n">t</span><span class="w"></span>
<span class="w">      </span><span class="k">val</span><span class="w"> </span><span class="n">x</span><span class="p">:</span><span class="w"> </span><span class="n">t</span><span class="w"> </span><span class="n">*</span><span class="w"> </span><span class="n">int</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">unit</span><span class="w"></span>
<span class="w">   </span><span class="k">end</span><span class="w"></span>
</pre></div></div></div>
<div class="paragraph"><p>is displayed as</p></div>
<div class="listingblock">
<div class="content monospaced">
<pre>signature SIG =
   sig
      type t = ?.t
      val x: (?.t * int) -&gt; unit
   end</pre>
</div></div>
<div class="paragraph"><p>Notice that <span class="monospaced">int</span> occurs without the <span class="monospaced">?.</span> prefix.</p></div>
<div class="paragraph"><p>MLton also uses a canonical name for each type in the signature, and
that name is used everywhere for that type, no matter what the input
signature looked like.  For example:</p></div>
<div class="listingblock">
<div class="content"><div class="highlight"><pre><span class="k">signature</span><span class="w"> </span><span class="n">SIG</span><span class="w"> </span><span class="p">=</span><span class="w"></span>
<span class="w">   </span><span class="k">sig</span><span class="w"></span>
<span class="w">      </span><span class="k">type</span><span class="w"> </span><span class="n">t</span><span class="w"></span>
<span class="w">      </span><span class="k">type</span><span class="w"> </span><span class="n">u</span><span class="w"> </span><span class="p">=</span><span class="w"> </span><span class="n">t</span><span class="w"></span>
<span class="w">      </span><span class="k">val</span><span class="w"> </span><span class="n">x</span><span class="p">:</span><span class="w"> </span><span class="n">t</span><span class="w"></span>
<span class="w">      </span><span class="k">val</span><span class="w"> </span><span class="n">y</span><span class="p">:</span><span class="w"> </span><span class="n">u</span><span class="w"></span>
<span class="w">   </span><span class="k">end</span><span class="w"></span>
</pre></div></div></div>
<div class="paragraph"><p>is displayed as</p></div>
<div class="listingblock">
<div class="content monospaced">
<pre>signature SIG =
   sig
      type t = ?.t
      type u = ?.t
      val x: ?.t
      val y: ?.t
   end</pre>
</div></div>
<div class="paragraph"><p>Canonical names are always relative to the "top" of the signature,
even when used in nested substructures.  For example:</p></div>
<div class="listingblock">
<div class="content"><div class="highlight"><pre><span class="k">signature</span><span class="w"> </span><span class="n">S</span><span class="w"> </span><span class="p">=</span><span class="w"></span>
<span class="w">   </span><span class="k">sig</span><span class="w"></span>
<span class="w">      </span><span class="k">type</span><span class="w"> </span><span class="n">t</span><span class="w"></span>
<span class="w">      </span><span class="k">val</span><span class="w"> </span><span class="n">w</span><span class="p">:</span><span class="w"> </span><span class="n">t</span><span class="w"></span>
<span class="w">      </span><span class="k">structure</span><span class="w"> </span><span class="n">U</span><span class="p">:</span><span class="w"></span>
<span class="w">         </span><span class="k">sig</span><span class="w"></span>
<span class="w">            </span><span class="k">type</span><span class="w"> </span><span class="n">u</span><span class="w"></span>
<span class="w">            </span><span class="k">val</span><span class="w"> </span><span class="n">x</span><span class="p">:</span><span class="w"> </span><span class="n">t</span><span class="w"></span>
<span class="w">            </span><span class="k">val</span><span class="w"> </span><span class="n">y</span><span class="p">:</span><span class="w"> </span><span class="n">u</span><span class="w"></span>
<span class="w">         </span><span class="k">end</span><span class="w"></span>
<span class="w">      </span><span class="k">val</span><span class="w"> </span><span class="n">z</span><span class="p">:</span><span class="w"> </span><span class="n">U</span><span class="p">.</span><span class="n">u</span><span class="w"></span>
<span class="w">   </span><span class="k">end</span><span class="w"></span>
</pre></div></div></div>
<div class="paragraph"><p>is displayed as</p></div>
<div class="listingblock">
<div class="content monospaced">
<pre>signature S =
   sig
      type t = ?.t
      val w: ?.t
      val z: ?.U.u
      structure U:
         sig
            type u = ?.U.u
            val x: ?.t
            val y: ?.U.u
         end
   end</pre>
</div></div>
</div>
</div>
<div class="sect1">
<h2 id="_displaying_structures">Displaying structures</h2>
<div class="sectionbody">
<div class="paragraph"><p>When displaying structures, MLton uses signature constraints wherever
possible, combined with <span class="monospaced">where type</span> clauses to specify the meanings
of the types defined within the signature.  For example:</p></div>
<div class="listingblock">
<div class="content"><div class="highlight"><pre><span class="k">signature</span><span class="w"> </span><span class="n">SIG</span><span class="w"> </span><span class="p">=</span><span class="w"></span>
<span class="w">   </span><span class="k">sig</span><span class="w"></span>
<span class="w">      </span><span class="k">type</span><span class="w"> </span><span class="n">t</span><span class="w"></span>
<span class="w">      </span><span class="k">val</span><span class="w"> </span><span class="n">x</span><span class="p">:</span><span class="w"> </span><span class="n">t</span><span class="w"></span>
<span class="w">   </span><span class="k">end</span><span class="w"></span>
<span class="k">structure</span><span class="w"> </span><span class="n">S</span><span class="p">:</span><span class="w"> </span><span class="n">SIG</span><span class="w"> </span><span class="p">=</span><span class="w"></span>
<span class="w">   </span><span class="k">struct</span><span class="w"></span>
<span class="w">      </span><span class="k">type</span><span class="w"> </span><span class="n">t</span><span class="w"> </span><span class="p">=</span><span class="w"> </span><span class="n">int</span><span class="w"></span>
<span class="w">      </span><span class="k">val</span><span class="w"> </span><span class="n">x</span><span class="w"> </span><span class="p">=</span><span class="w"> </span><span class="mi">13</span><span class="w"></span>
<span class="w">   </span><span class="k">end</span><span class="w"></span>
<span class="k">structure</span><span class="w"> </span><span class="n">S2</span><span class="p">:&gt;</span><span class="w"> </span><span class="n">SIG</span><span class="w"> </span><span class="p">=</span><span class="w"> </span><span class="n">S</span><span class="w"></span>
</pre></div></div></div>
<div class="paragraph"><p>is displayed as</p></div>
<div class="listingblock">
<div class="content monospaced">
<pre>structure S: SIG
             where type t = int
structure S2: SIG
              where type t = S2.t
signature SIG =
   sig
      type t = ?.t
      val x: ?.t
   end</pre>
</div></div>
</div>
</div>
</div>
<div id="footnotes"><hr></div>
<div id="footer">
<div id="footer-text">
</div>
<div id="footer-badges">
</div>
</div>
</body>
</html>