O(1) conversion from mutable.Map to immutable.Map?

scala, scala-collections

Solution

There is a read only projection for mutable maps.

scala> collection.mutable.Map(1->2).readOnly
res0: scala.collection.Map[Int,Int] = ro-Map(1 -> 2)

As oxbow_lakes pointed out the underlying Map is still mutable and may change after the read-only projection is published to clients. The illusion of immutability has to addressed in code managing the map.

Problem

Is there a way to convert (wrap) a mutable Map to immutable in O(1) time (that is, not by copying the values, but similar to what is done in JavaConversions)

Original source