 normal_lpdf(y | 0, 1);
  }
}
...
model {
  alpha ~ unit_normal();
  beta ~ unit_normal();
  ...
}</code></pre>
<p>The ability to use the <code>unit_normal</code> function as a density is
keyed off its name ending in <code>_lpdf</code> (names ending in
<code>_lpmf</code> for probability mass functions work the same way).</p>
<p>In general, if <code>foo_lpdf</code> is defined to consume <span class="math inline">\(N + 1\)</span>
arguments, then</p>
<pre><code>y ~ foo(theta1, ..., thetaN);</code></pre>
<p>can