span> <span><a href="#type-node">node</a> <span class="arrow">&#45;&gt;</span></span> <a href="#type-node">node</a>)</span> <span class="arrow">&#45;&gt;</span></span> <span><a href="#type-node">node</a> <span class="arrow">&#45;&gt;</span></span> <span><a href="#type-t">t</a> <span class="arrow">&#45;&gt;</span></span> <a href="#type-node">node</a></span></code></div><div class="spec-doc"><p><code>fold f z t</code> is <code>f (... (f (f z n1) n2) ...) nn</code>, where <code>n1, ..., nn</code> are the nodes