gistfile1.scala

[info] Starting scala interpreter...
[info] 
Welcome to Scala version 2.10.0 (Java HotSpot(TM) 64-Bit Server VM, Java 1.6.0_43).
Type in expressions to have them evaluated.
Type :help for more information.

scala> import scalaz._
import scalaz._

scala> import Scalaz._
import Scalaz._

scala> val m: List[List[String]] = List(List("a", "b"), List("c", "d"))
m: List[List[String]] = List(List(a, b), List(c, d))

scala> m.sequence
res0: List[List[String]] = List(List(a, c), List(a, d), List(b, c), List(b, d))

scala> val l: Seq[List[String]] = Seq(List("a", "b"), List("c", "d"))
l: Seq[List[String]] = List(List(a, b), List(c, d))

scala> l.sequence
<console>:15: error: could not find implicit value for parameter F0: scalaz.Traverse[Seq]
              l.sequence
              ^
<console>:15: error: value sequence is not a member of Seq[List[String]]
              l.sequence
                ^

scala>