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Eta-Prelude-Classes-Monoid.html
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<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"><html xmlns="http://www.w3.org/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /><title>Eta.Prelude.Classes.Monoid</title><link href="ocean.css" rel="stylesheet" type="text/css" title="Ocean" /><script src="haddock-util.js" type="text/javascript"></script><script src="https://cdn.mathjax.org/mathjax/latest/MathJax.js?config=TeX-AMS-MML_HTMLorMML" type="text/javascript"></script><script type="text/javascript">//<![CDATA[
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</script></head><body class="no-frame"><div id="package-header"><ul class="links" id="page-menu"><li><a href="index.html">Contents</a></li><li><a href="doc-index.html">Index</a></li></ul><p class="caption empty"> </p></div><div id="content"><div id="module-header"><table class="info"><tr><th>Safe Haskell</th><td>Safe</td></tr></table><p class="caption">Eta.Prelude.Classes.Monoid</p></div><div id="table-of-contents"><p class="caption">Contents</p><ul><li><a href="#g:1">Monoid neutral element</a></li><li><a href="#g:2">Monoid reduction</a></li><li><a href="#g:3">Append operator</a></li></ul></div><div id="description"><p class="caption">Description</p><div class="doc"><p>The <code>Monoid</code> type class defines that a type
can have an <code><a href="Eta-Prelude-Classes-Monoid.html#v:append">append</a></code> operation which can be used
to append two things of the same type</p><p>The List, and String types are examples of
instances of <code>Monoid</code>.</p><p><em>Mnemonic: Appendable</em></p></div></div><div id="synopsis"><p id="control.syn" class="caption expander" onclick="toggleSection('syn')">Synopsis</p><ul id="section.syn" class="hide" onclick="toggleSection('syn')"><li class="src short"><a href="#v:append">append</a> :: Monoid a => a -> a -> a</li><li class="src short"><a href="#v:neutral">neutral</a> :: Monoid a => a</li><li class="src short"><a href="#v:concat">concat</a> :: Monoid a => [a] -> a</li><li class="src short"><a href="#v:-60--43--62-">(<+>)</a> :: Monoid a => a -> a -> a</li></ul></div><div id="interface"><h1>Documentation</h1><div class="top"><p class="src"><a id="v:append" class="def">append</a> :: Monoid a => a -> a -> a <a href="#v:append" class="selflink">#</a></p><div class="doc"><p>Appends two values.</p><pre class="screen"><code class="prompt">>>> </code><strong class="userinput"><code>append "Hello " "world!"
</code></strong>"Hello world!"
</pre></div></div><h3 id="g:1">Monoid neutral element</h3><div class="top"><p class="src"><a id="v:neutral" class="def">neutral</a> :: Monoid a => a <a href="#v:neutral" class="selflink">#</a></p><div class="doc"><p>A <code>Monoid</code> also requires that the type has a neutral
element that does not affect concatenation.</p><p>$
>>> import Prelude (String, Int)</p><pre class="screen"><code class="prompt">>>> </code><strong class="userinput"><code>neutral :: String
</code></strong>""
</pre><pre class="screen"><code class="prompt">>>> </code><strong class="userinput"><code>neutral :: [Int]
</code></strong>[]
</pre></div></div><h3 id="g:2">Monoid reduction</h3><div class="top"><p class="src"><a id="v:concat" class="def">concat</a> :: Monoid a => [a] -> a <a href="#v:concat" class="selflink">#</a></p><div class="doc"><p>You can reduce a list of elements that implement the
<code>Monoid</code> type class by using <code><a href="Eta-Prelude-Classes-Monoid.html#v:concat">concat</a></code></p><pre class="screen"><code class="prompt">>>> </code><strong class="userinput"><code>concat ["Hello ", "world", "!"]
</code></strong>"Hello world!"
</pre></div></div><h3 id="g:3">Append operator</h3><div class="top"><p class="src"><a id="v:-60--43--62-" class="def">(<+>)</a> :: Monoid a => a -> a -> a <a href="#v:-60--43--62-" class="selflink">#</a></p><div class="doc"><p>Operator for the <code><a href="Eta-Prelude-Classes-Monoid.html#v:append">append</a></code> operation</p><pre class="screen"><code class="prompt">>>> </code><strong class="userinput"><code>"Hello " <+> "world!"
</code></strong>"Hello world!"
</pre></div></div></div></div><div id="footer"><p>Produced by <a href="http://www.haskell.org/haddock/">Haddock</a> version 2.17.4</p></div></body></html>