The problem, by the way, is that the use of nested literals (string and dictionary, here) causes the compiler to do a very large search to resolve the types. A quoted string, e.g. &quot;foo&quot;, could be any type that conforms to StringLiteralConvertible. It&#x27;s evaluating all permutations of potential type assignments to each literal that appears.<p>I thought they fixed this, though. I filed it for Array&lt;Array&lt;Int&gt;&gt; long ago, and they patched that case. <a href="https:&#x2F;&#x2F;twitter.com&#x2F;kongtomorrow&#x2F;status&#x2F;565844856690339841" rel="nofollow">https:&#x2F;&#x2F;twitter.com&#x2F;kongtomorrow&#x2F;status&#x2F;565844856690339841</a>