`cask.Response` is now covariant

1 files changed, 9 insertions, 0 deletions

diff --git a/cask/src/cask/internal/Conversion.scala b/cask/src/cask/internal/Conversion.scala
new file mode 100644
index 0000000..e6a5a47
--- /dev/null
+++ b/cask/src/cask/internal/Conversion.scala
@@ -0,0 +1,9 @@
+package cask.internal
+
+import scala.annotation.implicitNotFound
+
+@implicitNotFound("Cannot return ${T} as a ${V} response")
+class Conversion[T, V](val f: T => V)
+object Conversion{
+  def create[T, V](implicit f: T => V) = new Conversion(f)
+}