Wanted: List[(A, B)] => (List[A], List[B])

gistfile1.txt

scala> import scalaz._
import scalaz._

scala> import scalaz.std.list._
import scalaz.std.list._

scala> import scalaz.std.tuple._
import scalaz.std.tuple._

scala> import scalaz.syntax.bitraverse._
import scalaz.syntax.bitraverse._

scala> List((1, "a"), (2, "b")).bisequence
<console>:20: error: could not find implicit value for parameter F0: scalaz.Unapply2[scalaz.Bitraverse,List[(Int, java.lang.String)]]
              List((1, "a"), (2, "b")).bisequence
                  ^

scala> List((1, "a"), (2, "b")).bisequence[List, Int, String]
<console>:20: error: could not find implicit value for parameter F0: scalaz.Unapply2[scalaz.Bitraverse,List[(Int, java.lang.String)]]
              List((1, "a"), (2, "b")).bisequence[List, Int, String]
                  ^

scala> List((1, "a"), (2, "b")).sequence
<console>:20: error: value sequence is not a member of List[(Int, java.lang.String)]
              List((1, "a"), (2, "b")).sequence
                                       ^

scala> import scalaz.syntax.traverse._
import scalaz.syntax.traverse._

scala> List((1, "a"), (2, "b")).sequence
<console>:23: error: could not find implicit value for parameter ev: scalaz.Leibniz.===[(Int, java.lang.String),G[B]]
              List((1, "a"), (2, "b")).sequence