386 lines
11 KiB
HTML
386 lines
11 KiB
HTML
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
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"http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
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<html>
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<meta http-equiv="Content-Type" content="text/html; charset=UTF-8"/>
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<head>
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<title>Penlight Documentation</title>
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<link rel="stylesheet" href="../ldoc.css" type="text/css" />
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<body>
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<div id="container">
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<div id="product">
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<div id="product_logo"></div>
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<div id="product_name"><big><b></b></big></div>
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<div id="product_description"></div>
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<div id="main">
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<!-- Menu -->
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<br/>
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<h1>Penlight</h1>
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<ul>
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<li><a href="../index.html">Index</a></li>
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</ul>
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<h2>Contents</h2>
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<ul>
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<li><a href="#Functions">Functions</a></li>
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</ul>
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<h2>Modules</h2>
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<ul>
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<li><a href="../modules/pl.html">pl</a></li>
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<li><a href="../modules/pl.Date.html">pl.Date</a></li>
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<li><a href="../modules/pl.List.html">pl.List</a></li>
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<li><a href="../modules/pl.Map.html">pl.Map</a></li>
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<li><a href="../modules/pl.MultiMap.html">pl.MultiMap</a></li>
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<li><a href="../modules/pl.OrderedMap.html">pl.OrderedMap</a></li>
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<li><a href="../modules/pl.Set.html">pl.Set</a></li>
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<li><a href="../modules/pl.app.html">pl.app</a></li>
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<li><a href="../modules/pl.array2d.html">pl.array2d</a></li>
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<li><a href="../modules/pl.class.html">pl.class</a></li>
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<li><a href="../modules/pl.comprehension.html">pl.comprehension</a></li>
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<li><a href="../modules/pl.config.html">pl.config</a></li>
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<li><a href="../modules/pl.data.html">pl.data</a></li>
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<li><a href="../modules/pl.dir.html">pl.dir</a></li>
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<li><a href="../modules/pl.file.html">pl.file</a></li>
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<li><strong>pl.func</strong></li>
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<li><a href="../modules/pl.input.html">pl.input</a></li>
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<li><a href="../modules/pl.lapp.html">pl.lapp</a></li>
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<li><a href="../modules/pl.lexer.html">pl.lexer</a></li>
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<li><a href="../modules/pl.luabalanced.html">pl.luabalanced</a></li>
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<li><a href="../modules/pl.operator.html">pl.operator</a></li>
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<li><a href="../modules/pl.path.html">pl.path</a></li>
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<li><a href="../modules/pl.permute.html">pl.permute</a></li>
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<li><a href="../modules/pl.pretty.html">pl.pretty</a></li>
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<li><a href="../modules/pl.seq.html">pl.seq</a></li>
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<li><a href="../modules/pl.sip.html">pl.sip</a></li>
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<li><a href="../modules/pl.strict.html">pl.strict</a></li>
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<li><a href="../modules/pl.stringio.html">pl.stringio</a></li>
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<li><a href="../modules/pl.stringx.html">pl.stringx</a></li>
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<li><a href="../modules/pl.tablex.html">pl.tablex</a></li>
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<li><a href="../modules/pl.template.html">pl.template</a></li>
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<li><a href="../modules/pl.test.html">pl.test</a></li>
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<li><a href="../modules/pl.text.html">pl.text</a></li>
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<li><a href="../modules/pl.utils.html">pl.utils</a></li>
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<li><a href="../modules/pl.xml.html">pl.xml</a></li>
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</ul>
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<h2>Topics</h2>
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<ul>
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<li><a href="../topics/01-introduction.md.html">01-introduction.md</a></li>
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<li><a href="../topics/02-arrays.md.html">02-arrays.md</a></li>
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<li><a href="../topics/03-strings.md.html">03-strings.md</a></li>
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<li><a href="../topics/04-paths.md.html">04-paths.md</a></li>
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<li><a href="../topics/05-dates.md.html">05-dates.md</a></li>
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<li><a href="../topics/06-data.md.html">06-data.md</a></li>
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<li><a href="../topics/07-functional.md.html">07-functional.md</a></li>
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<li><a href="../topics/08-additional.md.html">08-additional.md</a></li>
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<li><a href="../topics/09-discussion.md.html">09-discussion.md</a></li>
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</ul>
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<h2>Examples</h2>
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<ul>
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<li><a href="../examples/seesubst.lua.html">seesubst.lua</a></li>
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<li><a href="../examples/sipscan.lua.html">sipscan.lua</a></li>
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<li><a href="../examples/symbols.lua.html">symbols.lua</a></li>
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<li><a href="../examples/test-cmp.lua.html">test-cmp.lua</a></li>
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<li><a href="../examples/test-data.lua.html">test-data.lua</a></li>
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<li><a href="../examples/test-listcallbacks.lua.html">test-listcallbacks.lua</a></li>
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<li><a href="../examples/test-pretty.lua.html">test-pretty.lua</a></li>
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<li><a href="../examples/test-symbols.lua.html">test-symbols.lua</a></li>
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<li><a href="../examples/testapp.lua.html">testapp.lua</a></li>
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<li><a href="../examples/testclone.lua.html">testclone.lua</a></li>
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<li><a href="../examples/testconfig.lua.html">testconfig.lua</a></li>
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<li><a href="../examples/testglobal.lua.html">testglobal.lua</a></li>
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<li><a href="../examples/testinputfields.lua.html">testinputfields.lua</a></li>
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<li><a href="../examples/testinputfields2.lua.html">testinputfields2.lua</a></li>
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<li><a href="../examples/testxml.lua.html">testxml.lua</a></li>
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<li><a href="../examples/which.lua.html">which.lua</a></li>
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</ul>
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</div>
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<div id="content">
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<h1>Module <code>pl.func</code></h1>
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<p>Functional helpers like composition, binding and placeholder expressions.</p>
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<p> Placeholder expressions are useful for short anonymous functions, and were
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inspired by the Boost Lambda library.</p>
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<pre><code>> utils.import 'pl.func'
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> ls = List{10,20,30}
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> = ls:map(_1+1)
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{11,21,31}
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</code></pre>
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<p> They can also be used to <em>bind</em> particular arguments of a function.</p>
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<pre><code>> p = bind(print,'start>',_0)
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> p(10,20,30)
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> start> 10 20 30
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</code></pre>
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<p> See <a href="../topics/07-functional.md.html#Creating_Functions_from_Functions">the Guide</a></p>
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<p> Dependencies: <a href="../modules/pl.utils.html#">pl.utils</a> , <a href="../modules/pl.tablex.html#">pl.tablex</a> </p>
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<h2><a href="#Functions">Functions</a></h2>
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<table class="function_list">
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<tr>
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<td class="name" nowrap><a href="#import">import (tname, context)</a></td>
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<td class="summary">wrap a table of functions.</td>
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</tr>
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<tr>
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<td class="name" nowrap><a href="#register">register (fun, name)</a></td>
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<td class="summary">register a function for use in placeholder expressions.</td>
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</tr>
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<tr>
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<td class="name" nowrap><a href="#tail">tail (ls)</a></td>
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<td class="summary">all elements of a table except the first.</td>
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</tr>
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<tr>
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<td class="name" nowrap><a href="#repr">repr (e, lastpred)</a></td>
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<td class="summary">create a string representation of a placeholder expression.</td>
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</tr>
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<tr>
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<td class="name" nowrap><a href="#instantiate">instantiate (e)</a></td>
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<td class="summary">instantiate a PE into an actual function.</td>
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</tr>
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<tr>
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<td class="name" nowrap><a href="#I">I (e)</a></td>
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<td class="summary">instantiate a PE unless it has already been done.</td>
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</tr>
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<tr>
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<td class="name" nowrap><a href="#curry">curry (fn, p)</a></td>
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<td class="summary">bind the first parameter of the function to a value.</td>
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</tr>
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<tr>
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<td class="name" nowrap><a href="#compose">compose (f, g)</a></td>
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<td class="summary">create a function which chains two functions.</td>
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</tr>
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<tr>
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<td class="name" nowrap><a href="#bind">bind (fn, ...)</a></td>
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<td class="summary">bind the arguments of a function to given values.</td>
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</tr>
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</table>
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<br/>
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<br/>
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<h2><a name="Functions"></a>Functions</h2>
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<dl class="function">
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<dt>
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<a name = "import"></a>
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<strong>import (tname, context)</strong>
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</dt>
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<dd>
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wrap a table of functions. This makes them available for use in
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placeholder expressions.
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<h3>Parameters:</h3>
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<ul>
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<li><code><em>tname</em></code>: a table name</li>
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<li><code><em>context</em></code>: context to put results, defaults to environment of caller</li>
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</ul>
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</dd>
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<dt>
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<a name = "register"></a>
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<strong>register (fun, name)</strong>
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</dt>
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<dd>
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register a function for use in placeholder expressions.
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<h3>Parameters:</h3>
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<ul>
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<li><code><em>fun</em></code>: a function</li>
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<li><code><em>name</em></code>: an optional name</li>
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</ul>
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<h3>Returns:</h3>
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<ol>
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a placeholder functiond
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</ol>
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</dd>
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<dt>
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<a name = "tail"></a>
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<strong>tail (ls)</strong>
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</dt>
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<dd>
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all elements of a table except the first.
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<h3>Parameters:</h3>
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<ul>
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<li><code><em>ls</em></code>: a list-like table.</li>
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</ul>
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</dd>
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<dt>
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<a name = "repr"></a>
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<strong>repr (e, lastpred)</strong>
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</dt>
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<dd>
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create a string representation of a placeholder expression.
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<h3>Parameters:</h3>
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<ul>
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<li><code><em>e</em></code>: a placeholder expression</li>
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<li><code><em>lastpred</em></code>: not used</li>
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</ul>
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</dd>
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<dt>
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<a name = "instantiate"></a>
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<strong>instantiate (e)</strong>
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</dt>
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<dd>
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instantiate a PE into an actual function. First we find the largest placeholder used,
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e.g. _2; from this a list of the formal parameters can be build. Then we collect and replace
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any non-PE values from the PE, and build up a constant binding list.
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Finally, the expression can be compiled, and e.__PE_function is set.
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<h3>Parameters:</h3>
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<ul>
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<li><code><em>e</em></code>: a placeholder expression</li>
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</ul>
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<h3>Returns:</h3>
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<ol>
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a function
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</ol>
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</dd>
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<dt>
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<a name = "I"></a>
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<strong>I (e)</strong>
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</dt>
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<dd>
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instantiate a PE unless it has already been done.
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<h3>Parameters:</h3>
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<ul>
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<li><code><em>e</em></code>: a placeholder expression</li>
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</ul>
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<h3>Returns:</h3>
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<ol>
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the function
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</ol>
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</dd>
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<dt>
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<a name = "curry"></a>
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<strong>curry (fn, p)</strong>
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</dt>
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<dd>
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bind the first parameter of the function to a value.
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<h3>Parameters:</h3>
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<ul>
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<li><code><em>fn</em></code>: a function of one or more arguments</li>
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<li><code><em>p</em></code>: a value</li>
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</ul>
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<h3>Usage:</h3>
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<ul>
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<pre class="example">(curry(math.max,10))(20) == math.max(10,20)</pre>
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</ul>
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<h3>Returns:</h3>
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<ol>
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a function of one less argument
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</ol>
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</dd>
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<dt>
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<a name = "compose"></a>
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<strong>compose (f, g)</strong>
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</dt>
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<dd>
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create a function which chains two functions.
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<h3>Parameters:</h3>
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<ul>
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<li><code><em>f</em></code>: a function of at least one argument</li>
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<li><code><em>g</em></code>: a function of at least one argument</li>
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</ul>
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<h3>Usage:</h3>
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<ul>
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<pre class="example">printf = compose(io.write,string.format)</pre>
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</ul>
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<h3>Returns:</h3>
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<ol>
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a function
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</ol>
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</dd>
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<dt>
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<a name = "bind"></a>
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<strong>bind (fn, ...)</strong>
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</dt>
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<dd>
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bind the arguments of a function to given values.
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bind(fn,v,_2) is equivalent to curry(fn,v).
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<h3>Parameters:</h3>
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<ul>
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<li><code><em>fn</em></code>: a function of at least one argument</li>
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<li><code><em>...</em></code>: values or placeholder variables</li>
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</ul>
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<h3>Usage:</h3>
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<ul>
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<li><pre class="example">(bind(f,_1,a))(b) == f(a,b)</pre></li>
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<li><pre class="example">(bind(f,_2,_1))(a,b) == f(b,a)</pre></li>
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</ul>
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<h3>Returns:</h3>
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<ol>
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a function
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</ol>
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</dd>
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</dl>
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</div> <!-- id="content" -->
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</div> <!-- id="main" -->
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<div id="about">
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<i>generated by <a href="http://github.com/stevedonovan/LDoc">LDoc 1.2</a></i>
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</body>
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