Scala: working around the "illegal cyclic reference"
- by Paul Milovanov
Hi all,
I'm trying to implement a HashMap-based tree that'd support O(1) subtree lookup for a given root key. To that goal, I'm trying to do the following:
scala> type Q = HashMap[Char, Q]
<console>:6: error: illegal cyclic reference involving type Q
type Q = HashMap[Char, Q]
^
So the question is, is there a way for me to do something of the sort without resorting to the ugly HashMap[Char, Any] with subsequent casting of values to HashMap[Char, Any]?
Now, I also see that I can use something like the following to avoid the cyclic-reference error, and it might even be cleaner -- but it'd be nice to find out how to correctly do it the first way, just for the educational value.
import collections.mutable.HashMap
class LTree {
val children = new HashMap[Char, LTree]
}
Thanks a bunch.
