gistfile1.scala

scala> trait Assoc[K] { type V ; val value: V }
defined trait Assoc

scala> def mkAssoc[K, V0](k: K, v: V0): Assoc[k.type] { type V = V0 } =
     | new Assoc[k.type] { type V = V0 ; val value = v }
mkAssoc: [K, V0](k: K, v: V0)Assoc[k.type]{type V = V0}

scala> def lookup[K](k: K)(implicit assoc: Assoc[k.type]): assoc.V = assoc.value
lookup: [K](k: K)(implicit assoc: Assoc[k.type])assoc.V

scala> implicit def firstAssoc = mkAssoc(1, "Panda!")
firstAssoc: Assoc[1.type]{type V = String}

scala> implicit def secondAssoc = mkAssoc(2, 42)
secondAssoc: Assoc[2.type]{type V = Int}

scala> implicit def nameAssoc = mkAssoc("Name", "Mary")
nameAssoc: Assoc["Name".type]{type V = String}

scala> implicit def ageAssoc = mkAssoc("Age", 23)
ageAssoc: Assoc["Age".type]{type V = Int}

scala> lookup(1)
res0: String = Panda!

scala> lookup(2)
res1: Int = 42

scala> lookup("Name")
res2: String = Mary

scala> lookup("Age")
res3: Int = 23