title: Prettier breaks line in function definition when it has the type of returned function
body: <p>I have this function:</p>
  <pre><code>// before and after prettier
  
  const foo = (a: number) =&gt; (b: number) =&gt; {
    return a + b
  }
  
  </code></pre>
  <p>If I run prettier it will leave everything as is (which is desired behaviour for me).</p>
  <p>When I add type of returned function though it breaks a like for some reason.</p>
  <pre><code>// before prettier
  
  type NestedFuncType = (b: number) =&gt; number
  
  const foo = (a: number): NestedFuncType =&gt; b =&gt; {
    return a + b
  }
  
  </code></pre>
  <pre><code>// after prettier
  type NestedFuncType = (b: number) =&gt; number
  
  const foo =
    (a: number): NestedFuncType =&gt;
    (b) =&gt; {
      return a + b
    }
  
  </code></pre>
  <p>Is there anything I can do to prevent line breaks? My .prettierc:</p>
  <pre><code>{
    &quot;printWidth&quot;: 120,
    &quot;semi&quot;: false,
    &quot;singleQuote&quot;: true,
    &quot;trailingComma&quot;: &quot;es5&quot;
  }
  </code></pre>
  <p>Thanks.</p>