1 files changed, 32 insertions, 0 deletions
diff --git a/testsuite/tests/typecheck/should_compile/tc087.hs b/testsuite/tests/typecheck/should_compile/tc087.hs
new file mode 100644
index 0000000000..88317bad35
--- /dev/null
+++ b/testsuite/tests/typecheck/should_compile/tc087.hs
@@ -0,0 +1,32 @@
+{-# LANGUAGE Rank2Types #-}
+
+module ShouldSucceed where
+
+data SeqView t a              =  Null
+                              |  Cons a (t a)
+
+class PriorityQueue q where
+    empty			:: (Ord a) => q a
+    single			:: (Ord a) => a -> q a
+    insert			:: (Ord a) => a -> q a -> q a
+    meld			:: (Ord a) => q a -> q a -> q a
+    splitMin			:: (Ord a) => q a -> SeqView q a
+    insert a q		=  single a `meld` q
+
+toOrderedList q		=  case splitMin q of
+   Null			-> []
+   Cons a q		-> a : toOrderedList q
+
+insertMany x q		=  foldr insert q x
+pqSort q x		=  toOrderedList (insertMany x q)
+
+check			:: forall q. (PriorityQueue q) => (forall a. Ord a => q a) -> IO ()
+check empty		=  do
+    putStr "*** sorting\n"
+    out (pqSort empty [1 .. 99])
+    out (pqSort empty [1.0, 1.1 ..99.9])
+
+out				:: (Num a) => [a] -> IO ()
+out x | sum x == 0		=  putStr "ok\n"
+      | otherwise		=  putStr "ok\n"
+