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@milessabin
milessabin / conversions.scala
Created June 15, 2011 14:29
Code from my talk on representing polymorphic function values using type classes at the Scala eXchange ... full blog post to follow on http://www.chuusai.com/blog.
object Tuples {
import HLists._
implicit def tuple1ToHList[A](t : Product1[A]) = new { def hlisted : A :: HNil = t._1 :: HNil }
implicit def tuple2ToHList[A, B](t : Product2[A, B]) = new { def hlisted : A :: B :: HNil = t._1 :: t._2 :: HNil }
implicit def tuple3ToHList[A, B, C](t : Product3[A, B, C]) = new { def hlisted : A :: B :: C :: HNil = t._1 :: t._2 :: t._3 :: HNil }
implicit def hListToTuple1[A](h : A :: HNil) = new { def tupled : Tuple1[A] = Tuple1(h.head) }
implicit def hListToTuple2[A, B](h : A :: B :: HNil) = new { def tupled : (A, B) = (h.head, h.tail.head) }
implicit def hListToTuple3[A, B, C](h : A :: B :: C :: HNil) = new { def tupled : (A, B, C) = (h.head, h.tail.head, h.tail.tail.head) }