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diff --git a/compiler/utils/OrdList.lhs b/compiler/utils/OrdList.lhs
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+%
+% (c) The AQUA Project, Glasgow University, 1993-1998
+%
+
+This is useful, general stuff for the Native Code Generator.
+
+Provide trees (of instructions), so that lists of instructions
+can be appended in linear time.
+
+\begin{code}
+module OrdList (
+	OrdList, 
+        nilOL, isNilOL, unitOL, appOL, consOL, snocOL, concatOL,
+        fromOL, toOL, foldrOL, foldlOL
+) where
+
+infixl 5  `appOL`
+infixl 5  `snocOL`
+infixr 5  `consOL`
+
+data OrdList a
+  = Many [a]
+  | Two (OrdList a) (OrdList a)
+  | One  a
+  | None
+
+nilOL    :: OrdList a
+isNilOL  :: OrdList a -> Bool
+
+unitOL   :: a           -> OrdList a
+snocOL   :: OrdList a   -> a         -> OrdList a
+consOL   :: a           -> OrdList a -> OrdList a
+appOL    :: OrdList a   -> OrdList a -> OrdList a
+concatOL :: [OrdList a] -> OrdList a
+
+nilOL        = None
+unitOL as    = One as
+snocOL as b  = Two as (One b)
+consOL a  bs = Two (One a) bs
+concatOL aas = foldr Two None aas
+
+isNilOL None        = True
+isNilOL (One _)     = False
+isNilOL (Two as bs) = isNilOL as && isNilOL bs
+isNilOL (Many xs)   = null xs
+
+appOL None bs   = bs
+appOL as   None = as
+appOL as   bs   = Two as bs
+
+mapOL :: (a -> b) -> OrdList a -> OrdList b
+mapOL f None = None
+mapOL f (One x) = One (f x)
+mapOL f (Two x y) = Two (mapOL f x) (mapOL f y)
+mapOL f (Many xs) = Many (map f xs)
+
+instance Functor OrdList where
+  fmap = mapOL
+
+foldrOL :: (a->b->b) -> b -> OrdList a -> b
+foldrOL k z None        = z
+foldrOL k z (One x)     = k x z
+foldrOL k z (Two b1 b2) = foldrOL k (foldrOL k z b2) b1
+foldrOL k z (Many xs)   = foldr k z xs
+
+foldlOL :: (b->a->b) -> b -> OrdList a -> b
+foldlOL k z None        = z
+foldlOL k z (One x)     = k z x
+foldlOL k z (Two b1 b2) = foldlOL k (foldlOL k z b1) b2
+foldlOL k z (Many xs)   = foldl k z xs
+
+fromOL :: OrdList a -> [a]
+fromOL ol 
+   = flat ol []
+     where
+        flat None      rest = rest
+        flat (One x)   rest = x:rest
+        flat (Two a b) rest = flat a (flat b rest)
+	flat (Many xs) rest = xs ++ rest
+
+toOL :: [a] -> OrdList a
+toOL xs = Many xs
+\end{code}