Lists can be heterogeneous and often are, yet equal recurses on them. If you have list-based code that uses equal, you have extra work to do if you want to con

Lists can be heterogeneous and often are, yet equal recurses on them. If you have list-based code that uses equal, you have extra work to do if you want to convert it to vectors. Vectors comparable with equal make good hash table keys when heterogeneous keys are needed which don't need the structural flexibility of lists.