选择无形HList而不是案例类

Question

What are the advantages of using a shapeless HList over a case class in Scala? In what situations would you not want to use a HList?

Answer 1

You may want to read these questions first:

• Are HLists nothing more than a convoluted way of writing tuples?

• How can I use the new Slick 2.0 HList to overcome 22 column limit?

Essentially case classes are tuples underneath, which in turn map to a Java classes . However HList is a List like data structure. So you may have to traverse the list to access a particular member HList . This is more costly than using a case class member or a tuple member.