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<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
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<html xmlns="http://www.w3.org/1999/xhtml">
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<title>6.4. Lambda Expressions — Presto 0.206 Documentation</title>
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<span>Presto 0.206 Documentation</span></a></h1>
<h2 class="heading"><span>6.4. Lambda Expressions</span></h2>
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<div class="section" id="lambda-expressions">
<h1>6.4. Lambda Expressions</h1>
<p>Lambda expressions are written with <code class="docutils literal"><span class="pre">-></span></code>:</p>
<div class="highlight-sql"><div class="highlight"><pre><span></span><span class="n">x</span> <span class="o">-></span> <span class="n">x</span> <span class="o">+</span> <span class="mi">1</span>
<span class="p">(</span><span class="n">x</span><span class="p">,</span> <span class="n">y</span><span class="p">)</span> <span class="o">-></span> <span class="n">x</span> <span class="o">+</span> <span class="n">y</span>
<span class="n">x</span> <span class="o">-></span> <span class="n">regexp_like</span><span class="p">(</span><span class="n">x</span><span class="p">,</span> <span class="s1">'a+'</span><span class="p">)</span>
<span class="n">x</span> <span class="o">-></span> <span class="n">x</span><span class="p">[</span><span class="mi">1</span><span class="p">]</span> <span class="o">/</span> <span class="n">x</span><span class="p">[</span><span class="mi">2</span><span class="p">]</span>
<span class="n">x</span> <span class="o">-></span> <span class="k">IF</span><span class="p">(</span><span class="n">x</span> <span class="o">></span> <span class="mi">0</span><span class="p">,</span> <span class="n">x</span><span class="p">,</span> <span class="o">-</span><span class="n">x</span><span class="p">)</span>
<span class="n">x</span> <span class="o">-></span> <span class="n">COALESCE</span><span class="p">(</span><span class="n">x</span><span class="p">,</span> <span class="mi">0</span><span class="p">)</span>
<span class="n">x</span> <span class="o">-></span> <span class="k">CAST</span><span class="p">(</span><span class="n">x</span> <span class="k">AS</span> <span class="n">JSON</span><span class="p">)</span>
<span class="n">x</span> <span class="o">-></span> <span class="n">x</span> <span class="o">+</span> <span class="n">TRY</span><span class="p">(</span><span class="mi">1</span> <span class="o">/</span> <span class="mi">0</span><span class="p">)</span>
</pre></div>
</div>
<p>Most SQL expressions can be used in a lambda body, with a few exceptions:</p>
<ul class="simple">
<li>Subqueries are not supported. <code class="docutils literal"><span class="pre">x</span> <span class="pre">-></span> <span class="pre">2</span> <span class="pre">+</span> <span class="pre">(SELECT</span> <span class="pre">3)</span></code></li>
<li>Aggregations are not supported. <code class="docutils literal"><span class="pre">x</span> <span class="pre">-></span> <span class="pre">max(y)</span></code></li>
</ul>
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