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trait Builder[C[_], T] {
def +=(x: T)
def finalise: C[T]
}
trait Buildable[C[_]] {
def builder[T]: Builder[C,T]
}
object Test {
implicit object buildableList extends Buildable[List] {
def builder[T] = new Builder[List,T] {
val buf = new scala.collection.mutable.ListBuffer[T]
def +=(x: T) = buf += x
def finalise = buf.toList
}
}
def foo[C[_],T](x: T)(implicit b: Buildable[C]): C[T] = {
val builder = b.builder[T]
builder += x
builder.finalise
}
val l: List[Int] = foo(8)
}
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