Add IterableView.mapValues

[szeiger]

2.12:

scala> res0.mapValues(x=>  x^2)
res7: scala.collection.immutable.Map[String,Int] = Map(32 -> 1)

2.13:

scala> res0.mapValues(x=>  x^2).toMap
            ^
       warning: method mapValues in trait MapOps is deprecated (since 2.13.0): Use .view.mapValues(f). A future version will include a strict version of this method (for now, .view.mapValues(f).toMap).
res9: scala.collection.immutable.Map[String,Int] = Map(32 -> 1)

The recommended replacement does not compile in 2.12:

scala> Map(1 -> 2).view.mapValues(x => x*x)
<console>:12: error: value mapValues is not a member of scala.collection.IterableView[(Int, Int),scala.collection.immutable.Map[Int,Int]]
       Map(1 -> 2).view.mapValues(x => x*x)
                        ^

This could be remedied by adding an extension method for map-like IterableViews.

[SethTisue]

for anyone here on this ticket wondering about a workaround in the meantime, consider whether your code would still work if you replaced .mapValues(f) with .map{case (k, v) => (k, f(v)). and if you do need the laziness, perhaps you can .iterator your way to laziness

[japgolly]

Came here to report this, awesome that it's already been fixed! Any idea when the next release is coming?

[SethTisue]

@lrytz another possible rewrite