http://coderwiki.org/index.php?action=history&feed=atom&title=Sum_typeSum type - Revision history2026-05-19T03:45:41ZRevision history for this page on the wikiMediaWiki 1.44.0http://coderwiki.org/index.php?title=Sum_type&diff=106&oldid=prevDylan: add: other algebraic data types2025-08-15T08:56:15Z<p>add: other algebraic data types</p>
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<td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">Revision as of 08:56, 15 August 2025</td>
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<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>* [[Enum]]</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>* [[Enum]]</div></td></tr>
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<tr><td colspan="2" class="diff-side-deleted"></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;">== Other algebraic data types ==</ins></div></td></tr>
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</table>Dylanhttp://coderwiki.org/index.php?title=Sum_type&diff=105&oldid=prevDylan: new: info, example, types2025-08-15T08:55:47Z<p>new: info, example, types</p>
<p><b>New page</b></p><div>A '''sum type''' is a type of [[algebraic data type]]. It is a user-defined [[data type]] that stores a '''fixed set''' of possible values. In other words, it is a choice of possibilities as to the data it contains.<br />
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== Example ==<br />
Suppose we are in a '''zoo''' and want to keep track of animals in the zoo.<br />
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An example of a sum type could be an <code>Animal</code> [[data type]]. [[Variable|Variables]] of this data type can only contain one of these 4 [[Value|values]]:<br />
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* Parrot<br />
* Monkey<br />
* Tiger<br />
* Giraffe<br />
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This has the benefit of making [[invalid state]] impossible: we are guaranteed that the value of an <code>Animal</code> [[variable]] will always be one of the 4 above.<br />
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== Types of sum-types ==<br />
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* [[Enum]]<br />
* [[Tagged union]]</div>Dylan