"keyword">val</span> op_on_two_str : <span>(<a href="../../CostUtils/BasicCost/index.html#type-t">CostUtils.BasicCost.t</a> <span>&#45;&gt;</span> <a href="../../CostUtils/BasicCost/index.html#type-t">CostUtils.BasicCost.t</a> <span>&#45;&gt;</span> <span class="type-var">'a</span>)</span> <span>&#45;&gt;</span> <span>of_function:string</span> <span>&#45;&gt;</span> <a href="../../../IR/Exp/index.html#type-t">IR.Exp.t</a> <span>&#45;&gt;</span> <a href="../../../IR/Exp/index.html#type-t">IR.Exp.t</a> <span>