1<div class='api-docs-breadcrumbs'><a href="index.html">test</a> / <a href="./foo.html">foo</a></div>
2<h1>foo</h1>
3<a name="$foo()"></a>
4<div class="signature"><code><span class="keyword">fun </span><span class="identifier">foo</span><span class="symbol">(</span><span class="symbol">)</span><span class="symbol">: </span><span class="identifier">Unit</span></code></div>
5<div class="sample"><pre><code class="lang-kotlin">
6
7fun main(args: Array&lt;String&gt;) {
8//sampleStart
9val words = listOf("a", "abc", "ab", "def", "abcd")
10val byLength = words.groupBy { it.length }
11
12println(byLength.keys) // [1, 3, 2, 4]
13println(byLength.values) // [[a], [abc, def], [ab], [abcd]]
14
15val mutableByLength: MutableMap&lt;Int, MutableList&lt;String&gt;&gt; = words.groupByTo(mutableMapOf()) { it.length }
16// same content as in byLength map, but the map is mutable
17println("mutableByLength == byLength is ${mutableByLength == byLength}") // true
18//sampleEnd
19}</code></pre></div>
20