ref/type.html

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<h1 class="links">Type handling</h1>
Arc has functions to convert types and to determine the type of an object.
<h2>Type handling</h2>
<p><table class='arc'>
  <tr>
    <td class='arc'><a name='annotate'></a>
<img src='foundation.gif' title='Foundation'/>
<span class='op'>annotate</span> <span class='args'>type obj</span>
    <div class='desc'>Tags the object with the given type.</div>
    </td>
    <td class='arc'><pre>
&gt;(type (annotate 'mac car))
<span class="return">mac
</span></pre>
  </td></tr>
  <tr>
    <td class='arc'><a name='rep'></a>
<img src='foundation.gif' title='Foundation'/>
<span class='op'>rep</span> <span class='args'>obj</span>
    <div class='desc'>Returns the underlying object for an annotated object</div>
    </td>
    <td class='arc'><pre>
&gt;(rep whilet)
<span class="return">#&lt;procedure: whilet&gt;
</span></pre>
  </td></tr>
  <tr>
    <td class='arc'><a name='sym'></a>
<img src='proc.gif' title='Procedure'/>
<span class='op'>sym</span> <span class='args'>x</span>
    <div class='desc'>Coerces x to a 'sym.</div>
    </td>
    <td class='arc'><pre>
&gt;(sym "a")
<span class="return">a
</span></pre>
  </td></tr>
  <tr>
    <td class='arc'><a name='coerce'></a>
<img src='foundation.gif' title='Foundation'/>
<span class='op'>coerce</span> <span class='args'>obj type [args]</span>
    <div class='desc'>Coerces object to a new type.  A char can be
  coerced to int, string, or sym.  A number can be coerced to int, char, or string
  (of specified base).  A string can be coerced to sym, cons (char list), or int (of
  specified base).  A list of characters can be coerced to a string.  A symbol
  can be coerced to a string.</div>
    </td>
    <td class='arc'><pre>
&gt;(coerce "a" 'sym)
<span class="return">a
</span></pre>
<pre>
&gt;(coerce 65 'char)
<span class="return">#\A
</span></pre>
<pre>
&gt;(coerce 65 'int 2)
<span class="return">65
</span></pre>
<pre>
&gt;(coerce "abc" 'cons)
<span class="return">(#\a #\b #\c)
</span></pre>
  </td></tr>
  <tr>
    <td class='arc'><a name='int'></a>
<img src='foundation.gif' title='Foundation'/>
<span class='op'>int</span> <span class='args'>x [base]</span>
    <div class='desc'>Coerces x to an integer.  New in arc3.</div>
    </td>
    <td class='arc'><pre>
&gt;(int "3.14")
<span class="return">3
</span></pre>
<pre>
&gt;(int "1111" 2)
<span class="return">15
</span></pre>
<pre>
&gt;(int #\a)
<span class="return">97
</span></pre>
  </td></tr>
  <tr>
    <td class='arc'><a name='type'></a>
<img src='foundation.gif' title='Foundation'/>
<span class='op'>type</span> <span class='args'>object</span>
    <div class='desc'>Returns the type of an object (as a symbol).
  Possibilities are cons, sym, fn, char, string, int, num, table, output,
  input, socket, exception, or mac.</div>
    </td>
    <td class='arc'><pre>
&gt;(type 1)
<span class="return">int
</span></pre>
<pre>
&gt;(type car)
<span class="return">fn
</span></pre>
  </td></tr>
</table>
<p>
Copyright 2008 Ken Shirriff.
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