implicit value not applied in scope - scala

Question

i'm trying to import a implicit Write declaration from an embedded object into a function that produces a JSON object based on a set of case classes.
case class TestModel(test:String)
object TestModel {
def manyToJSON(models: List[TestModel]) = {
import writes.micro
Json.toJson(models)
}
object writes {
implicit val micro = Json.writes[TestModel]
}
}
unfortunately, the scala compiler complains:
No Json serializer found for type List[models.TestModel]. Try to implement an implicit Writes or Format for this type.
the fun part is, if i'm using the write object as a pure expression within the method, its working.
object TestModel {
def manyToJSON(models: List[TestModel]) = {
import writes.micro
writes.micro
Json.toJson(models)
}
object writes {
implicit val micro = Json.writes[TestModel]
}
}
how would i have to change my code to have the implicit in scope?

Answer 1

the reason case class implicit is not working is that it is just a definition not value. Use case object will solve this issue like object. Consider this code:
object MainClass {
def main(args: Array[String]) {
TestModel.manyToJSON(Nil)
}
}
case class TestModel(test:String)
object TestModel {
def manyToJSON(models: List[TestModel]) = {
import writes._
def print(implicit x: Int) = {
println(x)
}
print // print 3
}
object writes {
implicit val x: Int = 3
//implicit val x = 3 //compilation error
}
}