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<!doctype html>
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<title>Монады</title>
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<span class="corp-name"><b>NAUMEN </b></span>Роман Деньгин
</div>
<div class="slides">
<section>
<h1>Монады</h1>
<div style="position: relative; right: 0;">Роман Деньгин</div>
</section>
</div>
<div class="slides">
<section>
<div style="background: #ffffff; overflow:auto;width:auto;border:solid gray;border-width:.1em .1em .1em .8em;padding:.2em .6em;">
<pre style="margin: 0; line-height: 125%">
<span style="color: #008800; font-weight: bold">def</span> mapList<span style="color: #333333">[</span><span style="color: #333399; font-weight: bold">A</span>, <span style="color: #333399; font-weight: bold">B</span><span style="color: #333333">](</span>f<span style="color: #008800; font-weight: bold">:</span> <span style="color: #333399; font-weight: bold">A</span> <span style="color: #333333">=></span> B<span style="color: #333333">)</span><span style="color: #008800; font-weight: bold">:</span> <span style="color: #333399; font-weight: bold">List</span><span style="color: #333333">[</span><span style="color: #333399; font-weight: bold">A</span><span style="color: #333333">]</span> <span style="color: #008800; font-weight: bold">=></span> <span style="color: #BB0066; font-weight: bold">List</span><span style="color: #333333">[</span><span style="color: #333399; font-weight: bold">B</span><span style="color: #333333">]</span> <span style="color: #008800; font-weight: bold">=</span> <span style="color: #333333">{</span> <span style="color: #333333">(</span>listA<span style="color: #008800; font-weight: bold">:</span> <span style="color: #333399; font-weight: bold">List</span><span style="color: #333333">[</span><span style="color: #333399; font-weight: bold">A</span><span style="color: #333333">])</span> <span style="color: #008800; font-weight: bold">=></span>
<span style="color: #008800; font-weight: bold">def</span> mapImpl<span style="color: #333333">(</span>input<span style="color: #008800; font-weight: bold">:</span> <span style="color: #333399; font-weight: bold">List</span><span style="color: #333333">[</span><span style="color: #333399; font-weight: bold">A</span><span style="color: #333333">],</span> buffer<span style="color: #008800; font-weight: bold">:</span> <span style="color: #333399; font-weight: bold">List</span><span style="color: #333333">[</span><span style="color: #333399; font-weight: bold">B</span><span style="color: #333333">])</span><span style="color: #008800; font-weight: bold">:</span> <span style="color: #333399; font-weight: bold">List</span><span style="color: #333333">[</span><span style="color: #333399; font-weight: bold">B</span><span style="color: #333333">]</span> <span style="color: #008800; font-weight: bold">=</span> input <span style="color: #008800; font-weight: bold">match</span> <span style="color: #333333">{</span>
<span style="color: #008800; font-weight: bold">case</span> head <span style="color: #333333">::</span> tail <span style="color: #008800; font-weight: bold">=></span> mapImpl<span style="color: #333333">(</span>tail<span style="color: #333333">,</span> buffer <span style="color: #333333">:+</span> f<span style="color: #333333">(</span>head<span style="color: #333333">))</span>
<span style="color: #008800; font-weight: bold">case</span> <span style="color: #008800; font-weight: bold">_</span> <span style="color: #008800; font-weight: bold">=></span> buffer
<span style="color: #333333">}</span>
mapImpl<span style="color: #333333">(</span>listA<span style="color: #333333">,</span> <span style="color: #BB0066; font-weight: bold">Nil</span><span style="color: #333333">)</span>
<span style="color: #333333">}</span>
</pre>
</div>
</section>
</div>
<div class="slides">
<section>
<div style="background: #ffffff; overflow:auto;width:auto;border:solid gray;border-width:.1em .1em .1em .8em;padding:.2em .6em;">
<pre style="margin: 0; line-height: 125%">
<span style="color: #008800; font-weight: bold">def</span> mapOption<span style="color: #333333">[</span><span style="color: #333399; font-weight: bold">A</span>, <span style="color: #333399; font-weight: bold">B</span><span style="color: #333333">](</span>f<span style="color: #008800; font-weight: bold">:</span> <span style="color: #333399; font-weight: bold">A</span> <span style="color: #333333">=></span> B<span style="color: #333333">)</span><span style="color: #008800; font-weight: bold">:</span> <span style="color: #333399; font-weight: bold">Option</span><span style="color: #333333">[</span><span style="color: #333399; font-weight: bold">A</span><span style="color: #333333">]</span> <span style="color: #008800; font-weight: bold">=></span> <span style="color: #BB0066; font-weight: bold">Option</span><span style="color: #333333">[</span><span style="color: #333399; font-weight: bold">B</span><span style="color: #333333">]</span> <span style="color: #008800; font-weight: bold">=</span> <span style="color: #333333">{</span>
<span style="color: #008800; font-weight: bold">case</span> <span style="color: #BB0066; font-weight: bold">Some</span><span style="color: #333333">(</span>a<span style="color: #333333">)</span> <span style="color: #008800; font-weight: bold">=></span> <span style="color: #BB0066; font-weight: bold">Some</span><span style="color: #333333">(</span>f<span style="color: #333333">(</span>a<span style="color: #333333">))</span>
<span style="color: #008800; font-weight: bold">case</span> <span style="color: #008800; font-weight: bold">_</span> <span style="color: #008800; font-weight: bold">=></span> <span style="color: #BB0066; font-weight: bold">None</span>
<span style="color: #333333">}</span>
</pre>
</div>
</section>
</div>
<div class="slides">
<section>
<div style="background: #ffffff; overflow:auto;width:auto;border:solid gray;border-width:.1em .1em .1em .8em;padding:.2em .6em;">
<pre style="margin: 0; line-height: 125%">
<span style="color: #008800; font-weight: bold">def</span> mapFuture<span style="color: #333333">[</span><span style="color: #333399; font-weight: bold">A</span>, <span style="color: #333399; font-weight: bold">B</span><span style="color: #333333">](</span>f<span style="color: #008800; font-weight: bold">:</span> <span style="color: #333399; font-weight: bold">A</span> <span style="color: #333333">=></span> B<span style="color: #333333">)</span><span style="color: #008800; font-weight: bold">:</span> <span style="color: #333399; font-weight: bold">Future</span><span style="color: #333333">[</span><span style="color: #333399; font-weight: bold">A</span><span style="color: #333333">]</span> <span style="color: #008800; font-weight: bold">=></span> <span style="color: #BB0066; font-weight: bold">Future</span><span style="color: #333333">[</span><span style="color: #333399; font-weight: bold">B</span><span style="color: #333333">]</span>
<span class="fragment"><span style="color: #008800; font-weight: bold">def</span> mapTry<span style="color: #333333">[</span><span style="color: #333399; font-weight: bold">A</span>, <span style="color: #333399; font-weight: bold">B</span><span style="color: #333333">](</span>f<span style="color: #008800; font-weight: bold">:</span> <span style="color: #333399; font-weight: bold">A</span> <span style="color: #333333">=></span> B<span style="color: #333333">)</span><span style="color: #008800; font-weight: bold">:</span> <span style="color: #333399; font-weight: bold">Try</span><span style="color: #333333">[</span><span style="color: #333399; font-weight: bold">A</span><span style="color: #333333">]</span> <span style="color: #008800; font-weight: bold">=></span> <span style="color: #BB0066; font-weight: bold">Try</span><span style="color: #333333">[</span><span style="color: #333399; font-weight: bold">B</span><span style="color: #333333">]</span></span>
<span class="fragment"><span style="color: #008800; font-weight: bold">def</span> mapReads<span style="color: #333333">[</span><span style="color: #333399; font-weight: bold">A</span>, <span style="color: #333399; font-weight: bold">B</span><span style="color: #333333">](</span>f<span style="color: #008800; font-weight: bold">:</span> <span style="color: #333399; font-weight: bold">A</span> <span style="color: #333333">=></span> B<span style="color: #333333">)</span><span style="color: #008800; font-weight: bold">:</span> <span style="color: #333399; font-weight: bold">Reads</span><span style="color: #333333">[</span><span style="color: #333399; font-weight: bold">A</span><span style="color: #333333">]</span> <span style="color: #008800; font-weight: bold">=></span> <span style="color: #BB0066; font-weight: bold">Reads</span><span style="color: #333333">[</span><span style="color: #333399; font-weight: bold">B</span><span style="color: #333333">]</span></span>
</pre>
</div>
</section>
</div>
<div class="slides">
<section>
<h1>Функтор</h1>
<b>Функтор</b> - класс типов F[_], на которых можно определить операцию<br>
(A ⇒ B) ⇒ F[A] ⇒ F[B]
<div class="fragment" style="background: #ffffff; overflow:auto;width:auto;border:solid gray;border-width:.1em .1em .1em .8em;padding:.2em .6em;">
<pre style="margin: 0; line-height: 125%">
<span style="color: #008800; font-weight: bold">trait</span> <span style="color: #BB0066; font-weight: bold">Functor</span><span style="color: #333333">[</span><span style="color: #333399; font-weight: bold">F</span><span style="color: #333333">[</span><span style="color: #008800; font-weight: bold">_</span><span style="color: #333333">]]</span> <span style="color: #333333">{</span>
<span style="color: #008800; font-weight: bold">def</span> map<span style="color: #333333">[</span><span style="color: #333399; font-weight: bold">A</span>, <span style="color: #333399; font-weight: bold">B</span><span style="color: #333333">](</span>f<span style="color: #008800; font-weight: bold">:</span> <span style="color: #333399; font-weight: bold">A</span> <span style="color: #333333">=></span> B<span style="color: #333333">)</span><span style="color: #008800; font-weight: bold">:</span> <span style="color: #333399; font-weight: bold">F</span><span style="color: #333333">[</span><span style="color: #333399; font-weight: bold">A</span><span style="color: #333333">]</span> <span style="color: #008800; font-weight: bold">=></span> F<span style="color: #333333">[</span><span style="color: #333399; font-weight: bold">B</span><span style="color: #333333">]</span>
<span style="color: #333333">}</span>
<span class="fragment">map<span style="color: #333333">(</span><span style="color: #008800; font-weight: bold">_</span><span style="color: #333333">.</span>doubleValue<span style="color: #333333">)(</span><span style="color: #BB0066; font-weight: bold">List</span><span style="color: #333333">(</span><span style="color: #0000DD; font-weight: bold">1</span><span style="color: #333333">,</span> <span style="color: #0000DD; font-weight: bold">2</span><span style="color: #333333">,</span> <span style="color: #0000DD; font-weight: bold">3</span><span style="color: #333333">))</span> <span style="color: #888888">// List(2.0, 4.0, 6.0)</span></span>
<span class="fragment">map<span style="color: #333333">(</span><span style="color: #008800; font-weight: bold">_</span><span style="color: #333333">.</span>toString<span style="color: #333333">)(</span>map<span style="color: #333333">(</span><span style="color: #008800; font-weight: bold">_</span><span style="color: #333333">.</span>doubleValue<span style="color: #333333">)(</span><span style="color: #BB0066; font-weight: bold">List</span><span style="color: #333333">(</span><span style="color: #0000DD; font-weight: bold">1</span><span style="color: #333333">,</span> <span style="color: #0000DD; font-weight: bold">2</span><span style="color: #333333">,</span> <span style="color: #0000DD; font-weight: bold">3</span><span style="color: #333333">)))</span> <span style="color: #888888">// List("2.0", "4.0", "6.0")</span></span>
</pre>
</div>
</section>
</div>
<div class="slides">
<section>
<h1>Функтор</h1>
<div style="background: #ffffff; overflow:auto;width:auto;border:solid gray;border-width:.1em .1em .1em .8em;padding:.2em .6em;">
<pre style="margin: 0; line-height: 125%">
<span style="color: #008800; font-weight: bold">trait</span> <span style="color: #BB0066; font-weight: bold">FunctorInterface</span><span style="color: #333333">[</span><span style="color: #333399; font-weight: bold">A</span><span style="color: #333333">]</span> <span style="color: #333333">{</span>
<span style="color: #008800; font-weight: bold">def</span> map<span style="color: #333333">[</span><span style="color: #333399; font-weight: bold">B</span><span style="color: #333333">](</span>f<span style="color: #008800; font-weight: bold">:</span> <span style="color: #333399; font-weight: bold">A</span> <span style="color: #333333">=></span> B<span style="color: #333333">)</span><span style="color: #008800; font-weight: bold">:</span> <span style="color: #333399; font-weight: bold">FunctorInterface</span><span style="color: #333333">[</span><span style="color: #333399; font-weight: bold">B</span><span style="color: #333333">]</span>
<span style="color: #333333">}</span>
<span style="color: #BB0066; font-weight: bold">Functor</span><span style="color: #333333">[</span><span style="color: #333399; font-weight: bold">List</span><span style="color: #333333">].</span>map<span style="color: #333333">(</span><span style="color: #008800; font-weight: bold">_</span><span style="color: #333333">.</span>doubleValue<span style="color: #333333">)(</span><span style="color: #BB0066; font-weight: bold">List</span><span style="color: #333333">(</span><span style="color: #0000DD; font-weight: bold">1</span><span style="color: #333333">,</span> <span style="color: #0000DD; font-weight: bold">2</span><span style="color: #333333">,</span> <span style="color: #0000DD; font-weight: bold">3</span><span style="color: #333333">))</span> <span style="color: #333333">~</span> <span style="color: #BB0066; font-weight: bold">List</span><span style="color: #333333">(</span><span style="color: #0000DD; font-weight: bold">1</span><span style="color: #333333">,</span> <span style="color: #0000DD; font-weight: bold">2</span><span style="color: #333333">,</span> <span style="color: #0000DD; font-weight: bold">3</span><span style="color: #333333">).</span>map<span style="color: #333333">(</span><span style="color: #008800; font-weight: bold">_</span><span style="color: #333333">.</span>doubleValue<span style="color: #333333">)</span>
</pre>
</div>
</section>
</div>
<div class="slides">
<section>
<h1>Функтор</h1>
<ul>
<li class="fragment">
Identity law<br>
<div style="background: #ffffff; overflow:auto;width:auto;border:solid gray;border-width:.1em .1em .1em .8em;padding:.2em .6em;">
<pre style="margin: 0; line-height: 125%">
<span style="color: #008800; font-weight: bold">def</span> identity<span style="color: #333333">[</span><span style="color: #333399; font-weight: bold">A</span><span style="color: #333333">](</span>x<span style="color: #008800; font-weight: bold">:</span> <span style="color: #333399; font-weight: bold">A</span><span style="color: #333333">)</span><span style="color: #008800; font-weight: bold">:</span><span style="color: #333399; font-weight: bold">A</span> <span style="color: #333333">=</span> x
<span style="color: #BB0066; font-weight: bold">List</span><span style="color: #333333">(</span><span style="color: #0000DD; font-weight: bold">1</span><span style="color: #333333">,</span> <span style="color: #0000DD; font-weight: bold">2</span><span style="color: #333333">,</span> <span style="color: #0000DD; font-weight: bold">3</span><span style="color: #333333">).</span>map<span style="color: #333333">(</span>identity<span style="color: #333333">)</span> <span style="color: #333333">==</span> identity<span style="color: #333333">(</span><span style="color: #BB0066; font-weight: bold">List</span><span style="color: #333333">(</span><span style="color: #0000DD; font-weight: bold">1</span><span style="color: #333333">,</span> <span style="color: #0000DD; font-weight: bold">2</span><span style="color: #333333">,</span> <span style="color: #0000DD; font-weight: bold">3</span><span style="color: #333333">))</span> <span style="color: #333333"><span class="fragment">== <span style="color: #BB0066; font-weight: bold">List</span><span style="color: #333333">(</span><span style="color: #0000DD; font-weight: bold">1</span><span style="color: #333333">,</span> <span style="color: #0000DD; font-weight: bold">2</span><span style="color: #333333">,</span> <span style="color: #0000DD; font-weight: bold">3</span><span style="color: #333333">)</span></span></span>
</pre>
</div>
</li>
<li class="fragment">
Associativity law
<div style="background: #ffffff; overflow:auto;width:auto;border:solid gray;border-width:.1em .1em .1em .8em;padding:.2em .6em;">
<pre style="margin: 0; line-height: 125%">
<span style="color: #008800; font-weight: bold">val</span> intToDouble<span style="color: #008800; font-weight: bold">:</span> <span style="color: #333399; font-weight: bold">Int</span> <span style="color: #333333">=></span> <span style="color: #BB0066; font-weight: bold">Double</span>
<span style="color: #008800; font-weight: bold">val</span> doubleToString<span style="color: #008800; font-weight: bold">:</span> <span style="color: #333399; font-weight: bold">Double</span> <span style="color: #333333">=></span> <span style="color: #BB0066; font-weight: bold">String</span>
<span style="color: #BB0066; font-weight: bold">List</span><span style="color: #333333">(</span><span style="color: #0000DD; font-weight: bold">1</span><span style="color: #333333">,</span> <span style="color: #0000DD; font-weight: bold">2</span><span style="color: #333333">,</span> <span style="color: #0000DD; font-weight: bold">3</span><span style="color: #333333">).</span>map<span style="color: #333333">(</span>intToDouble<span style="color: #333333">).</span>map<span style="color: #333333">(</span>doubleToString<span style="color: #333333">)</span>
<span style="color: #333333">==</span> <span style="color: #BB0066; font-weight: bold">List</span><span style="color: #333333">(</span><span style="color: #0000DD; font-weight: bold">1</span><span style="color: #333333">,</span> <span style="color: #0000DD; font-weight: bold">2</span><span style="color: #333333">,</span> <span style="color: #0000DD; font-weight: bold">3</span><span style="color: #333333">).</span>map<span style="color: #333333">(</span>intToDouble andThen doubleToString<span style="color: #333333">)</span>
<span style="color: #333333">==</span> <span style="color: #BB0066; font-weight: bold">List</span><span style="color: #333333">(</span><span style="background-color: #fff0f0">"1.0"</span><span style="color: #333333">,</span> <span style="background-color: #fff0f0">"2.0"</span><span style="color: #333333">,</span> <span style="background-color: #fff0f0">"3.0"</span><span style="color: #333333">)</span>
</pre>
</div>
</li>
</ul>
</section>
</div>
<div class="slides">
<section>
<h1>List-Функтор</h1>
<div style="background: #ffffff; overflow:auto;width:auto;border:solid gray;border-width:.1em .1em .1em .8em;padding:.2em .6em;">
<pre style="margin: 0; line-height: 125%">
<span style="color: #008800; font-weight: bold">val</span> listFunctor<span style="color: #008800; font-weight: bold">:</span> <span style="color: #333399; font-weight: bold">Functor</span><span style="color: #333333">[</span><span style="color: #333399; font-weight: bold">List</span><span style="color: #333333">]</span> <span style="color: #008800; font-weight: bold">=</span> <span style="color: #008800; font-weight: bold">new</span> <span style="color: #BB0066; font-weight: bold">Functor</span><span style="color: #333333">[</span><span style="color: #333399; font-weight: bold">List</span><span style="color: #333333">]</span> <span style="color: #333333">{</span>
<span style="color: #008800; font-weight: bold">def</span> map<span style="color: #333333">[</span><span style="color: #333399; font-weight: bold">A</span>, <span style="color: #333399; font-weight: bold">B</span><span style="color: #333333">](</span>f<span style="color: #008800; font-weight: bold">:</span> <span style="color: #333399; font-weight: bold">A</span> <span style="color: #333333">=></span> B<span style="color: #333333">)</span><span style="color: #008800; font-weight: bold">:</span> <span style="color: #333399; font-weight: bold">List</span><span style="color: #333333">[</span><span style="color: #333399; font-weight: bold">A</span><span style="color: #333333">]</span> <span style="color: #008800; font-weight: bold">=></span> <span style="color: #BB0066; font-weight: bold">List</span><span style="color: #333333">[</span><span style="color: #333399; font-weight: bold">B</span><span style="color: #333333">]</span> <span style="color: #008800; font-weight: bold">=</span> <span style="color: #333333">{</span> <span style="color: #333333">(</span>list<span style="color: #008800; font-weight: bold">:</span> <span style="color: #333399; font-weight: bold">List</span><span style="color: #333333">[</span><span style="color: #333399; font-weight: bold">A</span><span style="color: #333333">])</span> <span style="color: #008800; font-weight: bold">=></span>
<span style="color: #008800; font-weight: bold">if</span><span style="color: #333333">(</span>list<span style="color: #333333">.</span>isEmpty<span style="color: #333333">)</span> <span style="color: #333333">{</span>
<span style="color: #BB0066; font-weight: bold">List</span><span style="color: #333333">.</span>empty<span style="color: #333333">[</span><span style="color: #333399; font-weight: bold">B</span><span style="color: #333333">]</span>
<span style="color: #333333">}</span> <span style="color: #008800; font-weight: bold">else</span> <span style="color: #333333">{</span>
<span style="color: #008800; font-weight: bold">val</span> buffer <span style="color: #008800; font-weight: bold">=</span> <span style="color: #BB0066; font-weight: bold">ListBuffer</span><span style="color: #333333">.</span>empty<span style="color: #333333">[</span><span style="color: #333399; font-weight: bold">B</span><span style="color: #333333">]</span>
<span style="color: #008800; font-weight: bold">for</span><span style="color: #333333">(</span>i <span style="color: #008800; font-weight: bold"><-</span> <span style="color: #0000DD; font-weight: bold">0</span> until list<span style="color: #333333">.</span>size<span style="color: #333333">)</span> <span style="color: #333333">{</span>
buffer<span style="color: #333333">.</span>append<span style="color: #333333">(</span>f<span style="color: #333333">(</span>list<span style="color: #333333">(</span>i<span style="color: #333333">)))</span>
<span style="color: #333333">}</span>
buffer<span style="color: #333333">.</span>toList
<span style="color: #333333">}</span>
<span style="color: #333333">}</span>
<span style="color: #333333">}</span>
</pre>
</div>
</section>
</div>
<div class="slides">
<section>
<h1>List-Функтор</h1>
<div style="background: #ffffff; overflow:auto;width:auto;border:solid gray;border-width:.1em .1em .1em .8em;padding:.2em .6em;">
<pre style="margin: 0; line-height: 125%">
<span style="color: #888888">// 1. Identity law</span>
<span style="color: #BB0066; font-weight: bold">List</span><span style="color: #333333">(</span><span style="color: #0000DD; font-weight: bold">1</span><span style="color: #333333">,</span> <span style="color: #0000DD; font-weight: bold">2</span><span style="color: #333333">,</span> <span style="color: #0000DD; font-weight: bold">3</span><span style="color: #333333">).</span>map<span style="color: #333333">(</span>identity<span style="color: #333333">)</span> <span style="color: #888888">// List(1, 2, 3)</span>
<span style="color: #888888">// 2. Associativity law</span>
<span style="color: #BB0066; font-weight: bold">List</span><span style="color: #333333">(</span><span style="color: #0000DD; font-weight: bold">1</span><span style="color: #333333">,</span> <span style="color: #0000DD; font-weight: bold">2</span><span style="color: #333333">,</span> <span style="color: #0000DD; font-weight: bold">3</span><span style="color: #333333">)</span>
<span style="color: #333333">.</span>map<span style="color: #333333">(</span>intToDouble<span style="color: #333333">)</span> <span style="color: #888888">// List(1.0, 2.0, 3.0)</span>
<span style="color: #333333">.</span>map<span style="color: #333333">(</span>doubleToString<span style="color: #333333">)</span> <span style="color: #888888">// List("1.0", "2.0", "3.0")</span>
<span style="color: #BB0066; font-weight: bold">List</span><span style="color: #333333">(</span><span style="color: #0000DD; font-weight: bold">1</span><span style="color: #333333">,</span> <span style="color: #0000DD; font-weight: bold">2</span><span style="color: #333333">,</span> <span style="color: #0000DD; font-weight: bold">3</span><span style="color: #333333">)</span>
<span style="color: #333333">.</span>map<span style="color: #333333">(</span>itToDouble andThen doubleToString<span style="color: #333333">)</span> <span style="color: #888888">// List("1.0", "2.0", "3.0")</span>
</pre>
</div>
</section>
</div>
<div class="slides">
<section>
<h1>Try-Функтор</h1>
<div style="background: #ffffff; overflow:auto;width:auto;border:solid gray;border-width:.1em .1em .1em .8em;padding:.2em .6em;">
<pre style="margin: 0; line-height: 125%">
<span style="color: #008800; font-weight: bold">sealed</span> <span style="color: #008800; font-weight: bold">trait</span> <span style="color: #BB0066; font-weight: bold">Try</span><span style="color: #333333">[</span><span style="color: #333399; font-weight: bold">+T</span><span style="color: #333333">]</span>
<span style="color: #BB0066; font-weight: bold">final</span> <span style="color: #008800; font-weight: bold">case</span> <span style="color: #008800; font-weight: bold">class</span> <span style="color: #BB0066; font-weight: bold">Success</span><span style="color: #333333">[</span><span style="color: #333399; font-weight: bold">+T</span><span style="color: #333333">](</span>value<span style="color: #008800; font-weight: bold">:</span> <span style="color: #333399; font-weight: bold">T</span><span style="color: #333333">)</span> <span style="color: #008800; font-weight: bold">extends</span> <span style="color: #BB0066; font-weight: bold">Try</span><span style="color: #333333">[</span><span style="color: #333399; font-weight: bold">T</span><span style="color: #333333">]</span>
<span style="color: #008800; font-weight: bold">final</span> <span style="color: #008800; font-weight: bold">case</span> <span style="color: #008800; font-weight: bold">class</span> <span style="color: #BB0066; font-weight: bold">Failure</span><span style="color: #333333">[</span><span style="color: #333399; font-weight: bold">+T</span><span style="color: #333333">](</span>exception<span style="color: #008800; font-weight: bold">:</span> <span style="color: #333399; font-weight: bold">Exception</span><span style="color: #333333">)</span> <span style="color: #008800; font-weight: bold">extends</span> <span style="color: #BB0066; font-weight: bold">Try</span><span style="color: #333333">[</span><span style="color: #333399; font-weight: bold">T</span><span style="color: #333333">]</span>
<div class="fragment">
<span style="color: #008800; font-weight: bold">def</span> divide<span style="color: #333333">(</span>a<span style="color: #008800; font-weight: bold">:</span> <span style="color: #333399; font-weight: bold">Int</span><span style="color: #333333">,</span> b<span style="color: #008800; font-weight: bold">:</span> <span style="color: #333399; font-weight: bold">Int</span><span style="color: #333333">)</span><span style="color: #008800; font-weight: bold">:</span> <span style="color: #333399; font-weight: bold">Try</span><span style="color: #333333">[</span><span style="color: #333399; font-weight: bold">Int</span><span style="color: #333333">]</span> <span style="color: #008800; font-weight: bold">=</span>
<span style="color: #008800; font-weight: bold">try</span> <span style="color: #BB0066; font-weight: bold">Success</span><span style="color: #333333">(</span>a <span style="color: #333333">/</span> b<span style="color: #333333">)</span> <span style="color: #008800; font-weight: bold">catch</span> <span style="color: #333333">{</span>
<span style="color: #008800; font-weight: bold">case</span> <span style="color: #BB0066; font-weight: bold">NonFatal</span><span style="color: #333333">(</span>e<span style="color: #333333">)</span> <span style="color: #008800; font-weight: bold">=></span> <span style="color: #BB0066; font-weight: bold">Failure</span><span style="color: #333333">(</span>e<span style="color: #333333">)</span><span class="fragment" style="color: #888888"> // Не выбрасываем исключение => нет побочного эффекта</span>
<span style="color: #333333">}</span>
</div>
</pre>
</div>
</section>
</div>
<div class="slides">
<section>
<h1>Try-Функтор</h1>
<div style="background: #ffffff; overflow:auto;width:auto;border:solid gray;border-width:.1em .1em .1em .8em;padding:.2em .6em;">
<pre style="margin: 0; line-height: 125%">
<span style="color: #008800; font-weight: bold">def</span> printResult<span style="color: #333333">(</span>result<span style="color: #008800; font-weight: bold">:</span> <span style="color: #333399; font-weight: bold">Try</span><span style="color: #333333">[</span><span style="color: #333399; font-weight: bold">Int</span><span style="color: #333333">])</span> <span style="color: #008800; font-weight: bold">=</span> result <span style="color: #008800; font-weight: bold">match</span> <span style="color: #333333">{</span>
<span style="color: #008800; font-weight: bold">case</span> <span style="color: #BB0066; font-weight: bold">Success</span><span style="color: #333333">(</span>n<span style="color: #333333">)</span> <span style="color: #008800; font-weight: bold">=></span> println<span style="color: #333333">(</span>n<span style="color: #333333">)</span>
<span style="color: #008800; font-weight: bold">case</span> <span style="color: #BB0066; font-weight: bold">Failure</span><span style="color: #333333">(</span>e<span style="color: #333333">)</span> <span style="color: #008800; font-weight: bold">=></span> printnl<span style="color: #333333">(</span>s<span style="background-color: #fff0f0">"An error ${e.message}"</span><span style="color: #333333">)</span>
<span style="color: #333333">}</span>
<span class="fragment"><span style="color: #008800; font-weight: bold">def</span> divide2<span style="color: #333333">(</span>a<span style="color: #008800; font-weight: bold">:</span> <span style="color: #333399; font-weight: bold">Int</span><span style="color: #333333">,</span> b1<span style="color: #008800; font-weight: bold">:</span> <span style="color: #333399; font-weight: bold">Int</span><span style="color: #333333">,</span> b2<span style="color: #008800; font-weight: bold">:</span> <span style="color: #333399; font-weight: bold">Int</span><span style="color: #333333">)</span><span style="color: #008800; font-weight: bold">:</span> <span style="color: #333399; font-weight: bold">Try</span><span style="color: #333333">[</span><span style="color: #333399; font-weight: bold">Try</span><span style="color: #333333">[</span><span style="color: #333399; font-weight: bold">Int</span><span style="color: #333333">]]</span> <span style="color: #008800; font-weight: bold">=</span>
divide<span style="color: #333333">(</span>a<span style="color: #333333">,</span> b1<span style="color: #333333">).</span>map<span style="color: #333333">(</span>divide<span style="color: #333333">(</span><span style="color: #008800; font-weight: bold">_</span><span style="color: #333333">,</span> b2<span style="color: #333333">))</span></span>
<span class="fragment"><span style="color: #008800; font-weight: bold">def</span> printResult<span style="color: #333333">(</span>result<span style="color: #008800; font-weight: bold">:</span> <span style="color: #333399; font-weight: bold">Try</span><span style="color: #333333">[</span><span style="color: #333399; font-weight: bold">Try</span><span style="color: #333333">[</span><span style="color: #333399; font-weight: bold">Int</span><span style="color: #333333">]])</span> <span style="color: #008800; font-weight: bold">=</span> result <span style="color: #008800; font-weight: bold">match</span> <span style="color: #333333">{</span>
<span style="color: #008800; font-weight: bold">case</span> <span style="color: #BB0066; font-weight: bold">Success</span><span style="color: #333333">(</span><span style="color: #BB0066; font-weight: bold">Success</span><span style="color: #333333">(</span>n<span style="color: #333333">))</span> <span style="color: #008800; font-weight: bold">=></span> println<span style="color: #333333">(</span>n<span style="color: #333333">)</span>
<span style="color: #008800; font-weight: bold">case</span> <span style="color: #BB0066; font-weight: bold">Failure</span><span style="color: #333333">(</span>e<span style="color: #333333">)</span> <span style="color: #008800; font-weight: bold">=></span> printnl<span style="color: #333333">(</span>s<span style="background-color: #fff0f0">"An error ${e.message}"</span><span style="color: #333333">)</span>
<span style="color: #333333">}</span></span>
<span class="fragment" ><span style="color: #008800; font-weight: bold">def</span> sequentialDivision<span style="color: #333333">(</span>a<span style="color: #008800; font-weight: bold">:</span> <span style="color: #333399; font-weight: bold">Int</span><span style="color: #333333">,</span> b1<span style="color: #008800; font-weight: bold">:</span> <span style="color: #333399; font-weight: bold">Int</span><span style="color: #333333">,</span> bs<span style="color: #008800; font-weight: bold">:</span> <span style="color: #333399; font-weight: bold">Int</span> <span style="color: #333399; font-weight: bold">*</span><span style="color: #333333">)</span> <span style="color: #008800; font-weight: bold">=</span> bs <span style="color: #008800; font-weight: bold">match</span> <span style="color: #333333">{</span>
<span style="color: #008800; font-weight: bold">case</span> head <span style="color: #333333">::</span> tail <span style="color: #008800; font-weight: bold">=></span> divide<span style="color: #333333">(</span>a<span style="color: #333333">,</span> b1<span style="color: #333333">).</span>map<span style="color: #333333">(</span>sequentialDivision<span style="color: #333333">(</span><span style="color: #008800; font-weight: bold">_</span><span style="color: #333333">,</span> head<span style="color: #333333">,</span> tail<span style="color: #333333">))</span>
<span style="color: #008800; font-weight: bold">case</span> <span style="color: #008800; font-weight: bold">_</span> <span style="color: #008800; font-weight: bold">=></span> divide<span style="color: #333333">(</span>a<span style="color: #333333">,</span> b1<span style="color: #333333">)</span>
<span style="color: #333333">}</span></span>
</pre>
</div>
</section>
</div>
<div class="slides">
<section>
<div style="background: #ffffff; overflow:auto;width:auto;border:solid gray;border-width:.1em .1em .1em .8em;padding:.2em .6em;">
<pre style="margin: 0; line-height: 125%">
<span style="color: #008800; font-weight: bold">def</span> <span style="color: #BB0066; font-weight: bold">Bind</span><span style="color: #333333">[</span><span style="color: #333399; font-weight: bold">F</span><span style="color: #333333">[</span><span style="color: #008800; font-weight: bold">_</span><span style="color: #333333">]]</span> <span style="color: #333333">{</span>
<span style="color: #008800; font-weight: bold">def</span> <span style="color: #333333">>>=[</span><span style="color: #333399; font-weight: bold">A</span>, <span style="color: #333399; font-weight: bold">B</span><span style="color: #333333">](</span>f<span style="color: #008800; font-weight: bold">:</span> <span style="color: #333399; font-weight: bold">A</span> <span style="color: #333333">=></span> F<span style="color: #333333">[</span><span style="color: #333399; font-weight: bold">B</span><span style="color: #333333">])</span><span style="color: #008800; font-weight: bold">:</span> <span style="color: #333399; font-weight: bold">F</span><span style="color: #333333">[</span><span style="color: #333399; font-weight: bold">A</span><span style="color: #333333">]</span> <span style="color: #008800; font-weight: bold">=></span> F<span style="color: #333333">[</span><span style="color: #333399; font-weight: bold">B</span><span style="color: #333333">]</span>
<span class="fragment"><span style="color: #008800; font-weight: bold">def</span> flatMap<span style="color: #333333">[</span><span style="color: #333399; font-weight: bold">A</span>, <span style="color: #333399; font-weight: bold">B</span><span style="color: #333333">](</span>f<span style="color: #008800; font-weight: bold">:</span> <span style="color: #333399; font-weight: bold">A</span> <span style="color: #333333">=></span> F<span style="color: #333333">[</span><span style="color: #333399; font-weight: bold">B</span><span style="color: #333333">])</span><span style="color: #008800; font-weight: bold">:</span> <span style="color: #333399; font-weight: bold">F</span><span style="color: #333333">[</span><span style="color: #333399; font-weight: bold">A</span><span style="color: #333333">]</span> <span style="color: #008800; font-weight: bold">=></span> F<span style="color: #333333">[</span><span style="color: #333399; font-weight: bold">B</span><span style="color: #333333">]</span></span>
<span style="color: #333333">}</span>
<div class="fragment">
<span style="color: #008800; font-weight: bold">def</span> sequentialDivision<span style="color: #333333">(</span>a<span style="color: #008800; font-weight: bold">:</span> <span style="color: #333399; font-weight: bold">Int</span><span style="color: #333333">,</span> b1<span style="color: #008800; font-weight: bold">:</span> <span style="color: #333399; font-weight: bold">Int</span><span style="color: #333333">,</span> bs<span style="color: #008800; font-weight: bold">:</span> <span style="color: #333399; font-weight: bold">Int</span> <span style="color: #333399; font-weight: bold">*</span><span style="color: #333333">)</span><span style="color: #008800; font-weight: bold">:</span> <span style="color: #333399; font-weight: bold">Try</span><span style="color: #333333">[</span><span style="color: #333399; font-weight: bold">Int</span><span style="color: #333333">]</span> <span style="color: #008800; font-weight: bold">=</span> bs <span style="color: #008800; font-weight: bold">match</span> <span style="color: #333333">{</span>
<span style="color: #008800; font-weight: bold">case</span> head <span style="color: #333333">::</span> tail <span style="color: #008800; font-weight: bold">=></span> divide<span style="color: #333333">(</span>a<span style="color: #333333">,</span> b1<span style="color: #333333">).</span>flatMap<span style="color: #333333">(</span>sequentialDivision<span style="color: #333333">(</span><span style="color: #008800; font-weight: bold">_</span><span style="color: #333333">,</span> head<span style="color: #333333">,</span> tail<span style="color: #333333">))</span>
<span style="color: #008800; font-weight: bold">case</span> <span style="color: #008800; font-weight: bold">_</span> <span style="color: #008800; font-weight: bold">=></span> divide<span style="color: #333333">(</span>a<span style="color: #333333">,</span> b1<span style="color: #333333">)</span>
<span style="color: #333333">}</span></div>
</pre>
</div>
</section>
</div>
<div class="slides">
<section>
<h1>Монада</h1>
<b>Монада</b> - класс функторов M[_], на которых можно определить операцию<br>
(A ⇒ M[B]) ⇒ M[A] ⇒ M[B]
<div style="background: #ffffff; overflow:auto;width:auto;border:solid gray;border-width:.1em .1em .1em .8em;padding:.2em .6em;">
<pre style="margin: 0; line-height: 125%">
<span style="color: #008800; font-weight: bold">trait</span> <span style="color: #BB0066; font-weight: bold">Monad</span><span style="color: #333333">[</span><span style="color: #333399; font-weight: bold">M</span><span style="color: #333333">[</span><span style="color: #008800; font-weight: bold">_</span><span style="color: #333333">]]</span> <span style="color: #BB0066; font-weight: bold">extends</span> <span style="color: #BB0066; font-weight: bold">Functor</span><span style="color: #333333">[</span><span style="color: #333399; font-weight: bold">M</span><span style="color: #333333">]</span> <span style="color: #333333">{</span>
<span style="color: #008800; font-weight: bold">def</span> unit<span style="color: #333333">[</span><span style="color: #333399; font-weight: bold">A</span><span style="color: #333333">](</span>x<span style="color: #008800; font-weight: bold">:</span> A<span style="color: #333333">)</span><span style="color: #008800; font-weight: bold">:</span> <span style="color: #333399; font-weight: bold">M</span><span style="color: #333333">[</span><span style="color: #333399; font-weight: bold">A</span><span style="color: #333333">]</span>
<span style="color: #008800; font-weight: bold">def</span> flatMap<span style="color: #333333">[</span><span style="color: #333399; font-weight: bold">A</span>, <span style="color: #333399; font-weight: bold">B</span><span style="color: #333333">](</span>f<span style="color: #008800; font-weight: bold">:</span> <span style="color: #333399; font-weight: bold">A</span> <span style="color: #333333">=></span> M<span style="color: #333333">[</span><span style="color: #333399; font-weight: bold">B</span><span style="color: #333333">])</span><span style="color: #008800; font-weight: bold">:</span> <span style="color: #333399; font-weight: bold">M</span><span style="color: #333333">[</span><span style="color: #333399; font-weight: bold">A</span><span style="color: #333333">]</span> <span style="color: #008800; font-weight: bold">=></span> M<span style="color: #333333">[</span><span style="color: #333399; font-weight: bold">B</span><span style="color: #333333">]</span>
<span style="color: #008800; font-weight: bold">override</span> <span style="color: #008800; font-weight: bold">def</span> map<span style="color: #333333">[</span><span style="color: #333399; font-weight: bold">A</span>, <span style="color: #333399; font-weight: bold">B</span><span style="color: #333333">](</span>f<span style="color: #008800; font-weight: bold">:</span> <span style="color: #333399; font-weight: bold">A</span> <span style="color: #333333">=></span> B<span style="color: #333333">)</span><span style="color: #008800; font-weight: bold">:</span> <span style="color: #333399; font-weight: bold">M</span><span style="color: #333333">[</span><span style="color: #333399; font-weight: bold">A</span><span style="color: #333333">]</span> <span style="color: #008800; font-weight: bold">=></span> M<span style="color: #333333">[</span><span style="color: #333399; font-weight: bold">B</span><span style="color: #333333">]</span><span class="fragment"> <span style="color: #008800; font-weight: bold">=</span> flatMap<span style="color: #333333">(</span>f andThen unit<span style="color: #333333">)</span></span>
<span style="color: #333333">}</span>
</pre>
</div>
</section>
</div>
<div class="slides">
<section>
<h1>Монада</h1>
<ul>
<li class="fragment">
Right unit law <i>(bind(unit)(m) = m)</i><br>
<div style="background: #ffffff; overflow:auto;width:auto;border:solid gray;border-width:.1em .1em .1em .8em;padding:.2em .6em;">
<pre style="margin: 0; line-height: 125%">
optionX<span style="color: #333333">.</span>flatMap<span style="color: #333333">(</span><span style="color: #BB0066; font-weight: bold">Option</span><span style="color: #333333">(</span><span style="color: #008800; font-weight: bold">_</span><span style="color: #333333">))</span> <span style="color: #333333">==</span> optionX
</pre>
</div>
</li>
<li class="fragment">
Left unit law <i>(bind(foo)(unit(x)) == foo(x))</i><br>
<div style="background: #ffffff; overflow:auto;width:auto;border:solid gray;border-width:.1em .1em .1em .8em;padding:.2em .6em;">
<pre style="margin: 0; line-height: 125%">
<span style="color: #BB0066; font-weight: bold">Option</span><span style="color: #333333">(</span>x<span style="color: #333333">).</span>flatMap<span style="color: #333333">(</span>foo<span style="color: #333333">)</span> <span style="color: #333333">==</span> foo<span style="color: #333333">(</span>x<span style="color: #333333">)</span>
</pre>
</div>
</li>
<li class="fragment">
Associativity law <i>(bind(bind(m)(foo))(bar) = bind(m)(x => bind(foo(x))(bar)))</i><br>
<div style="background: #ffffff; overflow:auto;width:auto;border:solid gray;border-width:.1em .1em .1em .8em;padding:.2em .6em;">
<pre style="margin: 0; line-height: 125%">optionX<span style="color: #333333">.</span>flatMap<span style="color: #333333">(</span>foo<span style="color: #333333">).</span>flatMap<span style="color: #333333">(</span>bar<span style="color: #333333">)</span> <span style="color: #333333">==</span> optionX<span style="color: #333333">.</span>flatMap<span style="color: #333333">(</span>x <span style="color: #008800; font-weight: bold">=></span> foo<span style="color: #333333">(</span>x<span style="color: #333333">).</span>flatMap(bar)<span style="color: #333333">)</span>
</pre>
</div>
</li>
</ul>
</section>
</div>
<div class="slides">
<section>
<h1>Option-Монада</h1>
<div style="background: #ffffff; overflow:auto;width:auto;border:solid gray;border-width:.1em .1em .1em .8em;padding:.2em .6em;">
<pre style="margin: 0; line-height: 125%">
<span style="color: #008800; font-weight: bold">val</span> optionMonad<span style="color: #008800; font-weight: bold">:</span> <span style="color: #333399; font-weight: bold">Monad</span><span style="color: #333333">[</span><span style="color: #333399; font-weight: bold">Option</span><span style="color: #333333">]</span> <span style="color: #008800; font-weight: bold">=</span> <span style="color: #008800; font-weight: bold">new</span> <span style="color: #BB0066; font-weight: bold">Monad</span><span style="color: #333333">[</span><span style="color: #333399; font-weight: bold">Option</span><span style="color: #333333">]</span> <span style="color: #333333">{</span>
<span style="color: #008800; font-weight: bold">def</span> unit<span style="color: #333333">[</span><span style="color: #333399; font-weight: bold">A</span><span style="color: #333333">](</span>x<span style="color: #008800; font-weight: bold">:</span> A<span style="color: #333333">)</span> <span style="color: #008800; font-weight: bold">=</span> <span style="color: #008800; font-weight: bold">if</span><span style="color: #333333">(</span>x <span style="color: #333333">==</span> <span style="color: #008800; font-weight: bold">null</span><span style="color: #333333">)</span> <span style="color: #BB0066; font-weight: bold">None</span> <span style="color: #008800; font-weight: bold">else</span> <span style="color: #BB0066; font-weight: bold">Some</span><span style="color: #333333">(</span>x<span style="color: #333333">)</span>
<span style="color: #008800; font-weight: bold">def</span> flatMap<span style="color: #333333">[</span><span style="color: #333399; font-weight: bold">A</span>, <span style="color: #333399; font-weight: bold">B</span><span style="color: #333333">](</span>f<span style="color: #008800; font-weight: bold">:</span> <span style="color: #333399; font-weight: bold">A</span> <span style="color: #333333">=></span> <span style="color: #BB0066; font-weight: bold">Option</span><span style="color: #333333">[</span><span style="color: #333399; font-weight: bold">B</span><span style="color: #333333">])</span><span style="color: #008800; font-weight: bold">:</span> <span style="color: #333399; font-weight: bold">Option</span><span style="color: #333333">[</span><span style="color: #333399; font-weight: bold">A</span><span style="color: #333333">]</span> <span style="color: #008800; font-weight: bold">=></span> <span style="color: #BB0066; font-weight: bold">Option</span><span style="color: #333333">[</span><span style="color: #333399; font-weight: bold">B</span><span style="color: #333333">]</span> <span style="color: #008800; font-weight: bold">=</span> <span style="color: #333333">{</span>
<span style="color: #008800; font-weight: bold">case</span> <span style="color: #BB0066; font-weight: bold">Some</span><span style="color: #333333">(</span>a<span style="color: #333333">)</span> <span style="color: #008800; font-weight: bold">=></span> f<span style="color: #333333">(</span>a<span style="color: #333333">)</span>
<span style="color: #008800; font-weight: bold">case</span> <span style="color: #008800; font-weight: bold">_</span> <span style="color: #008800; font-weight: bold">=></span> <span style="color: #BB0066; font-weight: bold">None</span>
<span style="color: #333333">}</span>
<span style="color: #333333">}</span>
</pre>
</div>
</section>
</div>
<div class="slides">
<section>
<h1>Option-Монада</h1>
<div style="background: #ffffff; overflow:auto;width:auto;border:solid gray;border-width:.1em .1em .1em .8em;padding:.2em .6em;">
<pre style="margin: 0; line-height: 125%">
<span style="color: #888888">// 1. Right unit law</span>
<span style="color: #008800; font-weight: bold">val</span> optionX <span style="color: #008800; font-weight: bold">=</span> <span style="color: #BB0066; font-weight: bold">Option</span><span style="color: #333333">(</span><span style="color: #0000DD; font-weight: bold">12</span><span style="color: #333333">)</span> <span style="color: #888888">// Some(12)</span>
optionX<span style="color: #333333">.</span>flatMap<span style="color: #333333">(</span><span style="color: #BB0066; font-weight: bold">Option</span><span style="color: #333333">(</span><span style="color: #008800; font-weight: bold">_</span><span style="color: #333333">))</span> <span style="color: #888888">// Some(12)</span>
<span style="color: #BB0066; font-weight: bold">None</span><span style="color: #333333">.</span>flatMap<span style="color: #333333">(</span><span style="color: #BB0066; font-weight: bold">Option</span><span style="color: #333333">(</span><span style="color: #008800; font-weight: bold">_</span><span style="color: #333333">))</span> <span style="color: #888888">// None</span>
<span style="color: #888888">// 2. Left unit law</span>
<span style="color: #008800; font-weight: bold">val</span> intHalf<span style="color: #008800; font-weight: bold">:</span> <span style="color: #333399; font-weight: bold">Int</span> <span style="color: #333333">=></span> <span style="color: #BB0066; font-weight: bold">Option</span><span style="color: #333333">[</span><span style="color: #333399; font-weight: bold">Int</span><span style="color: #333333">]</span> <span style="color: #008800; font-weight: bold">=</span> x <span style="color: #008800; font-weight: bold">=></span> <span style="color: #008800; font-weight: bold">if</span><span style="color: #333333">(</span>x <span style="color: #333333">%</span> <span style="color: #0000DD; font-weight: bold">2</span> <span style="color: #333333">==</span> <span style="color: #0000DD; font-weight: bold">0</span><span style="color: #333333">)</span> <span style="color: #BB0066; font-weight: bold">Some</span><span style="color: #333333">(</span>x <span style="color: #333333">/</span> <span style="color: #0000DD; font-weight: bold">2</span><span style="color: #333333">)</span> <span style="color: #008800; font-weight: bold">else</span> <span style="color: #BB0066; font-weight: bold">None</span>
<span style="color: #BB0066; font-weight: bold">Option</span><span style="color: #333333">(</span><span style="color: #0000DD; font-weight: bold">5</span><span style="color: #333333">).</span>flatMap<span style="color: #333333">(</span>intHalf<span style="color: #333333">)</span> <span style="color: #888888">// None</span>
intHalf<span style="color: #333333">(</span><span style="color: #0000DD; font-weight: bold">5</span><span style="color: #333333">)</span> <span style="color: #888888">// None</span>
<span style="color: #BB0066; font-weight: bold">Option</span><span style="color: #333333">(</span><span style="color: #0000DD; font-weight: bold">4</span><span style="color: #333333">).</span>flatMap<span style="color: #333333">(</span>intHalf<span style="color: #333333">)</span> <span style="color: #888888">// Some(4)</span>
intHalf<span style="color: #333333">(</span><span style="color: #0000DD; font-weight: bold">4</span><span style="color: #333333">)</span> <span style="color: #888888">// Some(4)</span>
<span style="color: #888888">// 3. Associativity law</span>
<span style="color: #008800; font-weight: bold">val</span> intThird<span style="color: #008800; font-weight: bold">:</span> <span style="color: #333399; font-weight: bold">Int</span> <span style="color: #333333">=></span> <span style="color: #BB0066; font-weight: bold">Option</span><span style="color: #333333">[</span><span style="color: #333399; font-weight: bold">Int</span><span style="color: #333333">]</span> <span style="color: #008800; font-weight: bold">=</span> x <span style="color: #008800; font-weight: bold">=></span> <span style="color: #008800; font-weight: bold">if</span><span style="color: #333333">(</span>x <span style="color: #333333">%</span> <span style="color: #0000DD; font-weight: bold">3</span> <span style="color: #333333">==</span> <span style="color: #0000DD; font-weight: bold">0</span><span style="color: #333333">)</span> <span style="color: #BB0066; font-weight: bold">Some</span><span style="color: #333333">(</span>x <span style="color: #333333">/</span> <span style="color: #0000DD; font-weight: bold">3</span><span style="color: #333333">)</span> <span style="color: #008800; font-weight: bold">else</span> <span style="color: #BB0066; font-weight: bold">None</span>
optionX<span style="color: #333333">.</span>flatMap<span style="color: #333333">(</span>intHalf<span style="color: #333333">).</span>flatMap<span style="color: #333333">(</span>intThird<span style="color: #333333">)</span> <span style="color: #888888">// Some(2)</span>
optionX<span style="color: #333333">.</span>flatMap<span style="color: #333333">(</span>x <span style="color: #008800; font-weight: bold">=></span> intHalf<span style="color: #333333">(</span>x<span style="color: #333333">).</span>flatMap<span style="color: #333333">(</span>intThird<span style="color: #333333">))</span> <span style="color: #888888">// Some(2)</span>
</pre>
</div>
</section>
</div>
<div class="slides">
<section>
<h1>Монады в scala</h1>
<ul>
<li>List[T], Option[T]...</li>
<li class="fragment">Future[T] - ассинхронное выполнение кода</li>
<li class="fragment">Either[A, B] - сумма монад Left[A] и Right[B]</li>
</ul>
</section>
</div>
<div class="slides">
<section>
<h1>for-yield</h1>
<div style="background: #ffffff; overflow:auto;width:auto;border:solid gray;border-width:.1em .1em .1em .8em;padding:.2em .6em;">
<pre style="margin: 0; line-height: 125%">
<span style="color: #008800; font-weight: bold">val</span> foo <span style="color: #008800; font-weight: bold">=</span> <span style="color: #333333">(</span><span style="color: #008800; font-weight: bold">for</span><span style="color: #333333">(</span>i <span style="color: #008800; font-weight: bold"><-</span> <span style="color: #0000DD; font-weight: bold">0</span> to x<span style="color: #333333">)</span> <span style="color: #008800; font-weight: bold">yield</span> i <span style="color: #333333">*</span> i<span style="color: #333333">)</span> <span style="color: #888888">// Range(0*0, 1*1, ..., i*i)</span>
<span style="color: #008800; font-weight: bold">val</span> bar <span style="color: #008800; font-weight: bold">=</span> <span style="color: #008800; font-weight: bold">for</span><span style="color: #333333">(</span>i <span style="color: #008800; font-weight: bold"><-</span> <span style="color: #0000DD; font-weight: bold">0</span> to x<span style="color: #333333">;</span> j <span style="color: #008800; font-weight: bold"><-</span> <span style="color: #0000DD; font-weight: bold">0</span> to y<span style="color: #333333">)</span> <span style="color: #008800; font-weight: bold">yield</span> i <span style="color: #333333">*</span> j <span style="color: #888888">// Range(0*0, 0*1, ..., 0*j, 1*0, 1*1,..., i*j)</span>
<span class="fragment">foo <span style="color: #333333">~</span> <span style="color: #333333">(</span><span style="color: #0000DD; font-weight: bold">0</span> to x<span style="color: #333333">).</span>map<span style="color: #333333">(</span>i <span style="color: #008800; font-weight: bold">=></span> i <span style="color: #333333">*</span> i<span style="color: #333333">)</span></span>
<span class="fragment">bar <span style="color: #333333">~</span> <span style="color: #333333">(</span><span style="color: #0000DD; font-weight: bold">0</span> to x<span style="color: #333333">).</span>flatMap<span style="color: #333333">(</span>i <span style="color: #008800; font-weight: bold">=></span> <span style="color: #333333">(</span><span style="color: #0000DD; font-weight: bold">0</span> to y<span style="color: #333333">).</span>map<span style="color: #333333">(</span>j <span style="color: #008800; font-weight: bold">=></span> i <span style="color: #333333">*</span> j<span style="color: #333333">))</span></span>
</pre>
</div>
</section>
</div>
<div class="slides">
<section>
<h1>for-yield</h1>
<table>
<tbody>
<tr>
<td width="23%"></td>
<td width="25%">
<div style="background: #ffffff; overflow:auto;width:auto;border:solid gray;border-width:.1em .1em .1em .8em;padding:.2em .6em;"><pre style="margin: 0; line-height: 125%">
fooM
<span style="color: #333333">.</span>flatMap <span style="color: #333333">{</span> foo1 <span style="color: #008800; font-weight: bold">=></span>
f1<span style="color: #333333">(</span>foo1<span style="color: #333333">)</span>
<span style="color: #333333">.</span>flatMap <span style="color: #333333">{</span> foo2 <span style="color: #008800; font-weight: bold">=></span>
f2<span style="color: #333333">(</span>foo2<span style="color: #333333">)
.</span>flatMap<span style="color: #333333">(</span>foo3 <span style="color: #008800; font-weight: bold">=></span> f3<span style="color: #333333">(</span>foo3<span style="color: #333333">))</span>
<span style="color: #333333">}</span>
<span style="color: #333333">}</span>
</pre></div>
</td>
<td width="4%" style="vertical-align: middle">~</td>
<td width="25%">
<div style="background: #ffffff; overflow:auto;width:auto;border:solid gray;border-width:.1em .1em .1em .8em;padding:.2em .6em;"><pre style="margin: 0; line-height: 125%">
<span style="color: #008800; font-weight: bold">for</span> <span style="color: #333333">{</span>
foo1 <span style="color: #008800; font-weight: bold"><-</span> fooM
foo2 <span style="color: #008800; font-weight: bold"><-</span> f1<span style="color: #333333">(</span>foo1<span style="color: #333333">)</span>
foo3 <span style="color: #008800; font-weight: bold"><-</span> f2<span style="color: #333333">(</span>foo2<span style="color: #333333">)</span>
x <span style="color: #008800; font-weight: bold"> <-</span> f3<span style="color: #333333">(</span>foo3<span style="color: #333333">)</span>
<span style="color: #333333">}</span> <span style="color: #008800; font-weight: bold">yield</span> x
</pre></div>
</td>
<td width="23%"></td>
</tr>
</tbody>
</table>
</section>
</div>
<div class="slides">
<section>
<h1>for-yield</h1>
<div style="background: #ffffff; overflow:auto;width:auto;border:solid gray;border-width:.1em .1em .1em .8em;padding:.2em .6em;">
<pre style="margin: 0; line-height: 125%">
<span style="color: #008800; font-weight: bold">case</span> <span style="color: #008800; font-weight: bold">class</span> <span style="color: #BB0066; font-weight: bold">BucketBook</span><span style="color: #333333">(</span>userId<span style="color: #008800; font-weight: bold">:</span> <span style="color: #333399; font-weight: bold">UUID</span><span style="color: #333333">,</span> bookId<span style="color: #008800; font-weight: bold">:</span> <span style="color: #333399; font-weight: bold">UUID</span><span style="color: #333333">)</span>
<span style="color: #008800; font-weight: bold">case</span> <span style="color: #008800; font-weight: bold">class</span> <span style="color: #BB0066; font-weight: bold">Book</span><span style="color: #333333">(</span>id<span style="color: #008800; font-weight: bold">:</span> <span style="color: #333399; font-weight: bold">UUID</span><span style="color: #333333">,</span> authorId<span style="color: #008800; font-weight: bold">:</span> <span style="color: #333399; font-weight: bold">UUID</span><span style="color: #333333">)</span>
<span style="color: #008800; font-weight: bold">def</span> getUserBucket<span style="color: #333333">(</span>userId<span style="color: #008800; font-weight: bold">:</span> <span style="color: #333399; font-weight: bold">UUID</span><span style="color: #333333">)</span><span style="color: #008800; font-weight: bold">:</span> <span style="color: #333399; font-weight: bold">Future</span><span style="color: #333333">[</span><span style="color: #333399; font-weight: bold">Seq</span><span style="color: #333333">[</span><span style="color: #333399; font-weight: bold">BucketBook</span><span style="color: #333333">]]</span>
<span style="color: #008800; font-weight: bold">def</span> getBooks<span style="color: #333333">(</span>bookIds<span style="color: #008800; font-weight: bold">:</span> <span style="color: #333399; font-weight: bold">Seq</span><span style="color: #333333">[</span><span style="color: #333399; font-weight: bold">UUID</span><span style="color: #333333">])</span><span style="color: #008800; font-weight: bold">:</span> <span style="color: #333399; font-weight: bold">Future</span><span style="color: #333333">[</span><span style="color: #333399; font-weight: bold">Seq</span><span style="color: #333333">[</span><span style="color: #333399; font-weight: bold">Book</span><span style="color: #333333">]]</span>
<span style="color: #008800; font-weight: bold">def</span> getAuthors<span style="color: #333333">(</span>authorIds<span style="color: #008800; font-weight: bold">:</span> <span style="color: #333399; font-weight: bold">Seq</span><span style="color: #333333">[</span><span style="color: #333399; font-weight: bold">UUID</span><span style="color: #333333">])</span><span style="color: #008800; font-weight: bold">:</span> <span style="color: #333399; font-weight: bold">Future</span><span style="color: #333333">[</span><span style="color: #333399; font-weight: bold">Seq</span><span style="color: #333333">[</span><span style="color: #333399; font-weight: bold">Author</span><span style="color: #333333">]]</span>
</pre>
</div>
</section>
</div>
<div class="slides">
<section>
<h1>for-yield</h1>
<div style="background: #ffffff; overflow:auto;width:auto;border:solid gray;border-width:.1em .1em .1em .8em;padding:.2em .6em;">
<pre style="margin: 0; line-height: 125%">
<span style="color: #008800; font-weight: bold">def</span> bucketAuthors<span style="color: #333333">(</span>userId<span style="color: #008800; font-weight: bold">:</span> <span style="color: #333399; font-weight: bold">UUID</span><span style="color: #333333">)</span><span style="color: #008800; font-weight: bold">:</span> <span style="color: #333399; font-weight: bold">Future</span><span style="color: #333333">[</span><span style="color: #333399; font-weight: bold">Seq</span><span style="color: #333333">[</span><span style="color: #333399; font-weight: bold">Author</span><span style="color: #333333">]]</span> <span style="color: #008800; font-weight: bold">=</span>
getUserBucket<span style="color: #333333">(</span>userID<span style="color: #333333">)</span>
<span style="color: #333333">.</span>flatMap <span style="color: #333333">{</span> bucketBooks <span style="color: #008800; font-weight: bold">=></span>
<span style="color: #008800; font-weight: bold">val</span> bookIds <span style="color: #008800; font-weight: bold">=</span> bucketBooks<span style="color: #333333">.</span>map<span style="color: #333333">(</span><span style="color: #008800; font-weight: bold">_</span><span style="color: #333333">.</span>bookId<span style="color: #333333">)</span>
getBooks<span style="color: #333333">(</span>bookIds<span style="color: #333333">)</span>
<span style="color: #333333">.</span>flatMap <span style="color: #333333">{</span> books <span style="color: #008800; font-weight: bold">=></span>
<span style="color: #008800; font-weight: bold">val</span> authorIds <span style="color: #008800; font-weight: bold">=</span> books<span style="color: #333333">.</span>map<span style="color: #333333">(</span><span style="color: #008800; font-weight: bold">_</span><span style="color: #333333">.</span>authorId<span style="color: #333333">)</span>
getAuthors<span style="color: #333333">(</span>authorIds<span style="color: #333333">)</span>
<span style="color: #333333">}</span>
<span style="color: #333333">}</span>
</pre>
</div>
</section>
</div>
<div class="slides">
<section>
<h1>for-yield</h1>
<div style="background: #ffffff; overflow:auto;width:auto;border:solid gray;border-width:.1em .1em .1em .8em;padding:.2em .6em;">
<pre style="margin: 0; line-height: 125%">
<span style="color: #008800; font-weight: bold">def</span> bucketAuthors<span style="color: #333333">(</span>userId<span style="color: #008800; font-weight: bold">:</span> <span style="color: #333399; font-weight: bold">UUID</span><span style="color: #333333">)</span><span style="color: #008800; font-weight: bold">:</span> <span style="color: #333399; font-weight: bold">Future</span><span style="color: #333333">[</span><span style="color: #333399; font-weight: bold">Seq</span><span style="color: #333333">[</span><span style="color: #333399; font-weight: bold">Author</span><span style="color: #333333">]]</span> <span style="color: #008800; font-weight: bold">=</span>
<span style="color: #008800; font-weight: bold">for</span> <span style="color: #333333">{</span>
bucketBooks <span style="color: #008800; font-weight: bold"><-</span> getUserBucket<span style="color: #333333">(</span>userID<span style="color: #333333">)</span>
bookIds <span style="color: #008800; font-weight: bold">=</span> bucketBooks<span style="color: #333333">.</span>map<span style="color: #333333">(</span><span style="color: #008800; font-weight: bold">_</span><span style="color: #333333">.</span>bookId<span style="color: #333333">)</span>
books <span style="color: #008800; font-weight: bold"><-</span> getBooks<span style="color: #333333">(</span>bookIds<span style="color: #333333">)</span>
authorIds <span style="color: #008800; font-weight: bold">=</span> books<span style="color: #333333">.</span>map<span style="color: #333333">(</span><span style="color: #008800; font-weight: bold">_</span><span style="color: #333333">.</span>authorId<span style="color: #333333">)</span>
authors <span style="color: #008800; font-weight: bold"><-</span> getAuthors<span style="color: #333333">(</span>authorIds<span style="color: #333333">)</span>
<span style="color: #333333">}</span> <span style="color: #008800; font-weight: bold">yield</span> authors
</pre>
</div>
</section>
</div>
<div class="slides">
<section>
<h1>IO</h1>
<b>IO</b> - монада, кторая используется для функций с побочным эффектом.
<div class="fragment" style="background: #ffffff; overflow:auto;width:auto;border:solid gray;border-width:.1em .1em .1em .8em;padding:.2em .6em;">
<pre style="margin: 0; line-height: 125%">
scala<span style="color: #333333">></span> <span style="color: #008800; font-weight: bold">val</span> ioa<span style="color: #008800; font-weight: bold">:</span> <span style="color: #333399; font-weight: bold">IO</span><span style="color: #333333">[</span><span style="color: #333399; font-weight: bold">Unit</span><span style="color: #333333">]</span> <span style="color: #008800; font-weight: bold">=</span> <span style="color: #BB0066; font-weight: bold">IO</span> <span style="color: #333333">{</span> println<span style="color: #333333">(</span><span style="background-color: #fff0f0">"Hello, world!"</span><span style="color: #333333">)</span> <span style="color: #333333">}</span>
ioa<span style="color: #008800; font-weight: bold">:</span> <span style="color: #333399; font-weight: bold">IO</span><span style="color: #333333">[</span><span style="color: #333399; font-weight: bold">Unit</span><span style="color: #333333">]</span>
scala<span style="color: #333333">></span> <span style="color: #008800; font-weight: bold">val</span> program<span style="color: #008800; font-weight: bold">:</span> <span style="color: #333399; font-weight: bold">IO</span><span style="color: #333333">[</span><span style="color: #333399; font-weight: bold">String</span><span style="color: #333333">]</span> <span style="color: #008800; font-weight: bold">=</span>
<span style="color: #333333">| </span><span style="color: #008800; font-weight: bold">for</span> <span style="color: #333333">{</span>
<span style="color: #333333">| </span> <span style="color: #008800; font-weight: bold">_</span> <span style="color: #008800; font-weight: bold"><-</span> ioa
<span style="color: #333333">| </span> <span style="color: #008800; font-weight: bold">_</span> <span style="color: #008800; font-weight: bold"><-</span> ioa
<span style="color: #333333">| }</span> <span style="color: #008800; font-weight: bold">yield</span> <span style="background-color: #fff0f0">"Done!"</span>
program<span style="color: #008800; font-weight: bold">:</span> <span style="color: #333399; font-weight: bold">IO</span><span style="color: #333333">[</span><span style="color: #333399; font-weight: bold">String</span><span style="color: #333333">]</span>
scala<span style="color: #333333">></span> program<span style="color: #333333">.</span>unsafeRunSync<span style="color: #333333">()</span>
Hello, world!
Hello, world!
res0<span style="color: #008800; font-weight: bold">:</span> <span style="color: #333399; font-weight: bold">String</span> <span style="color: #333333">=</span> <span style="background-color: #fff0f0">"Done!"</span>
</pre>
</div>
</section>
</div>
<div class="slides">
<section>
<h1>Сторонние библиотеки</h1>
<table>
<tr>
<td style="vertical-align: middle">
Cats is a library which provides abstractions for functional programming in the Scala programming language. The name is a playful shortening of the word category.<br>
<i style="color: #888888">[Cats - библиотека, предоставляющая абстракции функционального программирования в Scala. Cats - игривое сокращение от слова "КАТегория"]</i>
</td>
<td width="20%"><img src="https://typelevel.org/cats-effect/img/cats-effect-logo.svg"></td>
</tr>
<tr>
<td style="vertical-align: middle">
It provides purely functional data structures to complement those from the Scala standard library<br>
<i style="color: #888888">[Предоставляет "чисто"-функциональные структуры данных для стандартной библиотеки Scala]</i>
</td>
<td width="20%"><img src="https://avatars.githubusercontent.com/u/183416?s=200&v=4"></td>
</tr>
</table>
</section>
</div>
<div class="slides">
<section>
<h1>Сторонние библиотеки</h1>
<ul>
<li>
Безопасность<br>
<i style="font-size:70%;color: #888888;">учтены многие недочеты стандартной библиотеки;</i>
</li>
<li class="fragment">
Расширенный функционал<br>
<i style="font-size:70%;color: #888888;">IO, mapN (map для TupleN[F[_], F[_], ...]), безопасные преобразования типов и т.д.;</i>
</li>
<li class="fragment">
Совместимость<br>
<i style="font-size:70%;color: #888888;">http4s, fs2, zio;</i>
</li>
<li class="fragment">
API в "более функциональном стиле"<br>
<i style="font-size:70%;color: #888888;">реализации с синтаксисом вида `>>=`, `>*` и т.д.</i>
</li>
</ul>
</section>
</div>
<div class="slides">
<section>
<h1>Спасибо за внимание</h1>
<h2>Вопросы?..</h2>
</section>
</div>
</div>
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