CODEWITHSUNDEEP
scalascala-collections
Roberto Bonvallet
Roberto Bonvallet

Reputation: 33319

Why is SortedMap with default value not sorted anymore?

Is there a reason for a SortedMap with a default value becoming a regular unsorted Map?

scala> val a = scala.collection.immutable.SortedMap(1 -> "uno", 3 -> "tres", 2 -> "dos")
a: scala.collection.immutable.SortedMap[Int,String] = Map(1 -> uno, 2 -> dos, 3 -> tres)

scala> a.withDefaultValue("")
res19: scala.collection.immutable.Map[Int,String] = Map(1 -> uno, 2 -> dos, 3 -> tres)

Upvotes: 0

Views: 258

Answers (1)

Sascha Kolberg
Sascha Kolberg

Reputation: 7152

The function withDefaultValue is implemented in Map and returns a wrapper type WithDefault that has the original Map as an underlying implementation.

Although the type is just Map[A, B], the underlying map is still your sorted map. Keys you add will still be sorted:

val a: SortedMap[Int, String] = scala.collection.immutable.SortedMap(1 -> "uno", 3 -> "tres", 2 -> "dos")
val b = a.withDefaultValue("")

val c = b + (4 -> "quattro")
val d = c + (0 -> "zero")

val e = d.toList

>> e: List[(Int, String)] = List((0,zero), (1,uno), (2,dos), (3,tres), (4,quattro))

Upvotes: 6

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