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diff --git a/tests/org.simantics.scl.compiler.tests/src/org/simantics/scl/compiler/tests/scl/RedBlackTrees.scl b/tests/org.simantics.scl.compiler.tests/src/org/simantics/scl/compiler/tests/scl/RedBlackTrees.scl
new file mode 100644
index 000000000..6f47bd013
--- /dev/null
+++ b/tests/org.simantics.scl.compiler.tests/src/org/simantics/scl/compiler/tests/scl/RedBlackTrees.scl
@@ -0,0 +1,101 @@
+import "Prelude"
+
+// Version 1, 'untyped'
+data Color = R | B 
+
+deriving instance Show Color
+
+data RB a = E | T Color (RB a) a (RB a)
+
+rbToList :: RB a -> [a]
+rbToList E = []
+rbToList (T _ l a r) = rbToList l + [a] + rbToList r
+
+deriving instance (Show a) => Show (RB a)
+
+// Insertion and membership test as by Okasaki
+insert :: Ord a => a -> RB a -> RB a
+insert x s = (match ins s with T _ a z b -> T B a z b) 
+    where
+        ins E = T R E x E
+        ins s = match s with
+          T B a y b ->
+              if x<y 
+              then balance (ins a) y b
+              else if x>y 
+              then balance a y (ins b)
+              else s
+          T R a y b ->
+              if x<y
+              then T R (ins a) y b
+              else if x>y 
+              then T R a y (ins b)
+              else s
+
+member :: Ord a => a -> RB a -> Boolean
+member x E = False
+member x (T _ a y b)
+    | x<y = member x a
+    | x>y = member x b
+    | otherwise = True
+
+// balance: first equation is new, to make it work with a weaker invariant
+balance :: RB a -> a -> RB a -> RB a
+balance (T R a x b) y (T R c z d) = T R (T B a x b) y (T B c z d)
+balance (T R (T R a x b) y c) z d = T R (T B a x b) y (T B c z d)
+balance (T R a x (T R b y c)) z d = T R (T B a x b) y (T B c z d)
+balance a x (T R b y (T R c z d)) = T R (T B a x b) y (T B c z d)
+balance a x (T R (T R b y c) z d) = T R (T B a x b) y (T B c z d)
+balance a x b = T B a x b
+
+// deletion a la SMK 
+delete :: Ord a => a -> RB a -> RB a
+delete x t = (match del t with 
+               T _ a y b -> T B a y b
+               _ -> E)
+      where
+        del E = E
+        del (T _ a y b)
+            | x<y = delformLeft a y b
+            | x>y = delformRight a y b
+            | otherwise = app a b
+        delformLeft a y b= match a with
+            T B _ _ _ -> balleft (del a) y b
+            _         -> T R (del a) y b
+        delformRight a y b = match b with
+            T B _ _ _ -> balright a y (del b)
+            _         -> T R a y (del b)
+
+balleft :: RB a -> a -> RB a -> RB a
+balleft (T R a x b) y c = T R (T B a x b) y c
+balleft bl x (T B a y b) = balance bl x (T R a y b)
+balleft bl x (T R (T B a y b) z c) = T R (T B bl x a) y (balance b z (sub1 c))
+
+balright :: RB a -> a -> RB a -> RB a
+balright a x (T R b y c) = T R a x (T B b y c)
+balright (T B a x b) y bl = balance (T R a x b) y bl
+balright (T R a x (T B b y c)) z bl = T R (balance (sub1 a) x b) y (T B c z bl)
+
+sub1 :: RB a -> RB a
+sub1 (T B a x b) = T R a x b
+sub1 _ = fail "invariance violation"
+
+app :: RB a -> RB a -> RB a
+app E x = x
+app x E = x
+app (T R a x b) (T R c y d) =
+    match app b c with
+        T R b' z c' -> T R(T R a x b') z (T R c' y d)
+        bc -> T R a x (T R bc y d)
+app (T B a x b) (T B c y d) = 
+    match app b c with
+        T R b' z c' -> T R(T B a x b') z (T B c' y d)
+        bc -> balleft a x (T B bc y d)
+app a (T R b x c) = T R (app a b) x c
+app (T R a x b) c = T R a x (app b c)
+
+testList = [4,6,2,7,4,7,2,5]
+
+main = rbToList (foldl (flip insert) E testList)
+--
+[2, 4, 5, 6, 7]
\ No newline at end of file