&#45;&gt;</span></span> <span class="type-var">'acc</span>)</span> <span class="arrow">&#45;&gt;</span></span>
  <span><span class="label">init</span>:<span class="type-var">'acc</span> <span class="arrow">&#45;&gt;</span></span>
  <span class="type-var">'acc</span></span></code></div><div class="spec-doc"><p>Same as <a href="#val-fold_joined"><code>fold_joined</code></a>, but wraps each line of stdin in <code>Ok</code> and lines of stderr in <code>Error</code> so they can be distinguished. This function us