85 lines
4.3 KiB
HTML
85 lines
4.3 KiB
HTML
<?xml version="1.0" encoding="utf-8"?>
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<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.1//EN" "http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd">
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<html xmlns="http://www.w3.org/1999/xhtml"><head>
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<title>.</title>
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<style type="text/css">
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* { color: #000; background: #fff; max-width: 700px; }
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tt, pre { background: #dedede; color: #111; font-family: monospace;
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white-space: pre; display: block; width: 100%; }
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.indentedcode { margin-left: 2em; margin-right: 2em; }
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.codeblock {
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background: #dedede; color: #111; font-family: monospace;
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box-shadow: 0 4px 8px 0 rgba(0, 0, 0, 0.2), 0 6px 20px 0 rgba(0, 0, 0, 0.19);
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padding: 7px;
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display: block;
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}
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.indentedlist { margin-left: 2em; color: #000; }
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span { white-space: pre; }
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.text { color: #000; white-space: pre; background: #dedede; }
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.colon { color: #000; background: #dedede; }
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.note { color: #000; background: #dedede; }
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.str { color: #000; text-decoration: underline; background: #dedede; }
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.num { color: #000; background: #dedede; font-weight: bold; font-style: italic; }
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.fnum { color: #000; font-weight: bold; background: #dedede; }
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.ptr { color: #000; font-weight: bold; background: #dedede; }
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.fetch { color: #000; font-style: italic; background: #dedede; }
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.store { color: #000; font-style: italic; background: #dedede; }
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.char { color: #000; background: #dedede; }
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.inst { color: #000; background: #dedede; }
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.defer { color: #000; background: #dedede; }
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.imm { color: #000; font-weight: bold; background: #dedede; }
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.prim { color: #000; font-weight: bolder; background: #dedede; }
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.tt { white-space: pre; font-family: monospace; background: #dedede; }
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.h1, .h2, .h3, .h4 { white-space: normal; }
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.h1 { font-size: 125%; }
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.h2 { font-size: 120%; }
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.h3 { font-size: 115%; }
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.h4 { font-size: 110%; }
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.hr { display: block; height: 2px; background: #000000; }
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</style>
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</head><body>
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<p><span class="h1">Lexical Scope</span>
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<br/><br/>
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RETRO has a single dictionary, but does provide a means of using
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lexical scope to keep this dictionary clean.
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<br/><br/>
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<span class="h2">Example</span>
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<br/><br/>
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<span class='codeblock'><span class="tt">```</span><br/><span class="tt">{{ </span><br/>
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<span class="tt"> <span class='str'>'A</span> var </span><br/>
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<span class="tt"> <span class='colon'>:++A</span> <span class='ptr'>&A</span> v:inc <span class='imm'>;</span> </span><br/>
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<span class="tt">---reveal--- </span><br/>
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<span class="tt"> <span class='colon'>:B</span> ++A ++A <span class='fetch'>@A</span> n:put nl <span class='imm'>;</span> </span><br/>
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<span class="tt">}} </span><br/>
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<span class="tt">```</span></span><br/><br/>
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In this example, the lexical namespace is created with <span class="tt">{{</span>. A
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variable (<span class="tt">A</span>) and word (<span class="tt">++A</span>) are defined. Then a marker is
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set with <span class="tt">---reveal---</span>. Another word (<span class="tt">B</span>) is defined, and the
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lexical area is closed with <span class="tt">}}</span>.
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<br/><br/>
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The headers between <span class="tt">{{</span> and <span class="tt">---reveal---</span> are then hidden from
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the dictionary, leaving only the headers between <span class="tt">---reveal---</span>
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and <span class="tt">}}</span> exposed.
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<br/><br/>
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<span class="h2">Notes</span>
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<br/><br/>
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This only affects word visibility within the scoped area. As an
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example:
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<br/><br/>
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<span class='codeblock'><span class="tt">```</span><br/><span class="tt"><span class='colon'>:a</span> <span class='num'>#1</span> <span class='imm'>;</span> </span><br/>
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<span class="tt"> </span><br/>
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<span class="tt">{{ </span><br/>
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<span class="tt"> <span class='colon'>:a</span> <span class='num'>#2</span> <span class='imm'>;</span> </span><br/>
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<span class="tt">---reveal--- </span><br/>
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<span class="tt"> <span class='colon'>:b</span> <span class='str'>'a</span> s:evaluate n:put <span class='imm'>;</span> </span><br/>
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<span class="tt">}} </span><br/>
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<span class="tt">```</span></span><br/><br/>
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In this, after <span class="tt">}}</span> closes the area, the <span class="tt">:a #2 ;</span> is hidden and
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the <span class="tt">s:evaluate</span> will find the <span class="tt">:a #1 ;</span> when <span class="tt">b</span> is run.
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</p>
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</body></html>
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