scalaz/scalaz — pull request #177 by S11001001 (2012-11-01 16:29:12+00:00)
Title: Provide instances/functions for immutable.IndexedSeq, not the mutable/im...

...mutable shared trait.

Because `scala.IndexedSeq` is `scala.collection.IndexedSeq`, whose covariant functor is just for pretend. With this change:

```scala
scala> Monad[IndexedSeq]
:12: error: could not find implicit value for parameter F: scalaz.Monad[IndexedSeq]
Monad[IndexedSeq]
^

scala> Monad[collection.immutable.IndexedSeq]
res1: scalaz.Monad[scala.collection.immutable.IndexedSeq] = scalaz.std.IndexedSeqSubInstances$$anon$1@36916057

scala> List(1,2,3).toIndexedSeq |+| List(4,5,6).toIndexedSeq
res2: scala.collection.immutable.IndexedSeq[Int] = Vector(1, 2, 3, 4, 5, 6)
```