scala2-3-UsingClauses-defs2.scala

case class U1[+T](t: T)
case class U2[+T](t: T)

def f1[T1,T2](name: String)(using u1: U1[T1])(using u2: U2[T2]): String = 
  s"f1: $name: $u1, $u2"
def f2[T1,T2](name: String)(using u1: U1[T1])(u2: U2[T2]): String =       
  s"f2: $name: $u1, $u2"

given u1i: U1[Int] = U1[Int](0)
given u2s: U2[String] = U2[String]("one")

f1("f1a")                           // f1: f1a: U1(0), U2(one)
f1("f1b")(using u1i)(using u2s)     // f1: f1b: U1(0), U2(one)

f2("f2a")(using u1i)(u2s)           // f2: f2a: U1(0), U2(one)
f2("f2b")(u2s)                      // f2: f2b: U1(0), U2(one)