Test Trac #10403

1 files changed, 19 insertions, 0 deletions

diff --git a/testsuite/tests/partial-sigs/should_compile/T10403.hs b/testsuite/tests/partial-sigs/should_compile/T10403.hs
new file mode 100644
index 0000000000..a33646da5d
--- /dev/null
+++ b/testsuite/tests/partial-sigs/should_compile/T10403.hs
@@ -0,0 +1,19 @@
+{-# LANGUAGE PartialTypeSignatures #-}
+module T10403 where
+
+data I a = I a
+instance Functor I where
+    fmap f (I a) = I (f a)
+
+newtype B t a = B a
+instance Functor (B t) where
+    fmap f (B a) = B (f a)
+
+newtype H f = H (f ())
+
+app :: H (B t)
+app = h (H . I) (B ())
+
+h :: _ => _
+--h :: Functor m => (a -> b) -> m a -> H m
+h f b = (H . fmap (const ())) (fmap f b)