span>(<span class="type-var">'a</span>, <span class="type-var">'v</span>, <span class="type-var">'b</span>, <span class="type-var">'m</span>)</span> <a href="index.html#type-exp">exp</a></span> * <span><span>(<span class="type-var">'b</span> * <span><span>(<span class="type-var">'a</span>, <span class="type-var">'v</span>, <span class="type-var">'b</span>, <span class="type-var">'m</span>)</span> <a href="index.html#type-exp">exp</a></span>)</span> list</span> * <span><span>(<span class="type-var">'a<