gistfile1.txt

scala> fooR
res15: scalaz.\/[String,Int] = \/-(1)

scala> def addOne[M[_]: Applicative](in: M[Int]) = in.map(_+1)
warning: there was one feature warning; re-run with -feature for details
addOne: [M[_]](in: M[Int])(implicit evidence$1: scalaz.Applicative[M])M[Int]

scala> addOne(fooR)
<console>:19: error: no type parameters for method addOne: (in: M[Int])(implicit evidence$1: scalaz.Applicative[M])M[Int] exist so that it can be applied to arguments (scalaz.\/[String,Int])
 --- because ---
argument expression's type is not compatible with formal parameter type;
 found   : scalaz.\/[String,Int]
 required: ?M[Int]
       addOne(fooR)
       ^
<console>:19: error: type mismatch;
 found   : scalaz.\/[String,Int]
 required: M[Int]
       addOne(fooR)
              ^
<console>:19: error: could not find implicit value for evidence parameter of type scalaz.Applicative[M]
       addOne(fooR)
             ^