Adding specific map methods to collections / functors - scala

Question

So I have a Vec2 class:
class Vec2(val x: Double, val y: Double)
{
def +(other: Vec2): Vec2 = Vec2(x + other.x, y + other.y)
def -(other: Vec2): Vec2 = Vec2(x - other.x, y - other.y)
def *(factor: Double): Vec2 = Vec2(x * factor, y * factor)
def /(divisor: Double): Vec2 = Vec2(x / divisor, y / divisor)
//Other methods omitted but you get the idea
}
I use this class a lot and I use it a lot in collections, so I would like short hand methods for .map(_ + other) .map(_ * factor) etc. I also want to add methods for addMultAll(second: Vec2, factor: Double) and multAddAll(factor: Double, second: Vec2) that I think would be clearer and safer as explicit methods.
So I chose the traversable class for my implicit. Is this the best / most general class that I can use? I have cribbed and modifed the map method from the scala source code. Is the code below correct? Will it work without problems?
object Vec2
{
import collection.mutable.{ Builder }
import scala.collection._
implicit class ImpVec2Class[+Repr](travLike: TraversableLike[Vec2, Repr])
{
def +++ [That](offset: Vec2)(implicit bf: generic.CanBuildFrom[Repr, Vec2, That]): That =
{
def builder =
{ // extracted to keep method size under 35 bytes, so that it can be JIT-inlined
val b = bf(travLike.repr)
b.sizeHint(travLike)
b
}
val b = builder
for (x <- travLike) b += x + offset
b.result
}
}
}
Do I need to do this for the map methods on Double if I want shortened methods, or does Scalaz / CATS already include them?

Answer 1

OK I'm going to post this as answer as its a slight improvement. I've removed the [That] type parameter on the method. I've also added an implict for Array[Vec2] as Array doesn't inherit from the Scala collection traits.
object Vec2
{
import collection.mutable.{ Builder }
import scala.collection._
implicit class ImpVec2Traversible[Repr](travLike: TraversableLike[Vec2, Repr])
{
def +++ (offset: Vec2)(implicit bf: generic.CanBuildFrom[Repr, Vec2, Repr]): Repr =
{
def builder =
{ // extracted to keep method size under 35 bytes, so that it can be JIT-inlined
val b = bf(travLike.repr)
b.sizeHint(travLike)
b
}
val b = builder
for (x <- travLike) b += x + offset
b.result
}
}
implicit class ImpVec2Array(arr: Array[Vec2])
{
def +++ (offset: Vec2): Array[Vec2] = arr.map(_ + offset)
}
}