-t"><a href="#type-t" class="anchor"></a><code><span class="keyword">type</span> <span>'a t</span></code></dt><dd><p>The principle type.</p><p>The type constructor <code>t</code> is the mapping of objects taking every type <code>'a</code> to a type <code>'a t</code>.</p></dd></dl><dl><dt class="spec value" id="val-map"><a href="#val-map" class="anchor"></a><code><span class="keyword">val</span> map : <span>f:<span>(<span class="type-var">'a</span> <span>&#45;&gt;</span> <span class="type-var">'b</span>)</sp