1 files changed, 23 insertions, 0 deletions
diff --git a/testsuite/tests/indexed-types/should_compile/Rules1.hs b/testsuite/tests/indexed-types/should_compile/Rules1.hs
new file mode 100644
index 0000000000..497c5bbeb9
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+++ b/testsuite/tests/indexed-types/should_compile/Rules1.hs
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+{-# LANGUAGE TypeFamilies #-}
+
+module Rules1 where
+
+class C a where
+  data T a
+
+instance (C a, C b) => C (a,b) where
+  data T (a,b) = TPair (T a) (T b)
+
+mapT :: (C a, C b) => (a -> b) -> T a -> T b
+mapT = undefined
+
+zipT :: (C a, C b) => T a -> T b -> T (a,b)
+zipT = undefined
+
+{-# RULES
+
+"zipT/mapT" forall f x y.
+  zipT (mapT f x) y = mapT (\(x,y) -> (f x, y)) (zipT x y)
+
+ #-}
+