scala function with implicit parameters - scala

Question

I have scala function as below,
scala> def getOrders: (String, String) => Seq[String] = (user: String, apiToken: String) => Seq.empty[String]
def getOrders: (String, String) => Seq[String]
scala> getOrders("prayagupd", "A1B2C3")
val res0: Seq[String] = List()
I want to pass in a third parameter as a implicit parameter but it does not seem possible for a function.
Here's what I want achieved using a method,
scala> def getOrders(user: String, apiToken: String)(implicit clientType: String) = Seq.empty[String]
def getOrders
(user: String, apiToken: String)(implicit clientType: String): Seq[String]
scala> implicit val clientType: String = "android"
implicit val clientType: String = "android"
scala> getOrders("prayagupd", "A1B2C3")
val res2: Seq[String] = List()
It does not seem possible because of the fact that apply function is predefined, which won't extra accept implicit parameter.
scala> new Function2[String, String, Seq[String]] {
def apply(user: String, apiToken: String): Seq[String] = Seq.empty
}
val res4: (String, String) => Seq[String] = <function2>
Overloadding does not do the trick either,
scala> new Function2[String, String, Seq[String]] {
def apply(user: String, apiToken: String): Seq[String] = Seq.empty
def apply(user: String, apiToken: String)(implicit clientType: String) = Seq("order1")
}
val res9: (String, String) => Seq[String] = <function2>
scala> implicit val clientType: String = "device"
implicit val clientType: String = "device"
scala> res9("prayagupd", "apiToken")
val res10: Seq[String] = List()
Is it that implicits are not recommended at all for functions or I'm missing something?

Answer 1

Experimental, your function might be expressed as follows without the implicit:
scala> def getOrders: (String, String) => (String) => Seq[String] = (user: String, apiToken: String) => (clientType: String) => Seq.empty[String]
def getOrders: (String, String) => String => Seq[String]
Poking around on that... it doesn't like implicit anywhere in there that might give you want you want.
An answer to a related question suggests the reason: getOrders "... is a method, not a function, and eta-expansion (which converts methods to functions) is not attempted until after implicit application." It seems that implicits are resolved at a method level, not a function level.