1 files changed, 20 insertions, 0 deletions
diff --git a/testsuite/tests/indexed-types/should_compile/ColGivenCheck.hs b/testsuite/tests/indexed-types/should_compile/ColGivenCheck.hs
new file mode 100644
index 0000000000..288c6e0608
--- /dev/null
+++ b/testsuite/tests/indexed-types/should_compile/ColGivenCheck.hs
@@ -0,0 +1,20 @@
+{-# LANGUAGE TypeFamilies #-}
+
+module ColInference  where 
+
+type family Elem c
+
+type instance Elem [e] = e
+
+class Col c where
+ isEmpty   :: c -> Bool
+ add       :: c -> Elem c -> c
+ headTail  :: c -> (Elem c,c)
+
+addAll :: (Col c1, Col c2, Elem c1 ~ Elem c2) => c1 -> c2 -> c2
+addAll c1 c2 
+	| isEmpty c1
+	= c2
+	| otherwise
+	= let (x,c1') = headTail c1
+	  in addAll c1' (add c2 x)