diff --git a/ons-hs.cabal b/ons-hs.cabal
index 9e36c32..3619633 100644
--- a/ons-hs.cabal
+++ b/ons-hs.cabal
@@ -21,6 +21,9 @@ library
                      , Orbit.Class
                      , Orbit.Products
                      , Support
+                     , Support.Rat
+                     , Support.OrdList
+                     , Support.Set
   build-depends:       base >= 4.7 && < 5
                      , containers
                      , data-ordlist
diff --git a/src/Support.hs b/src/Support.hs
index 14f2f08..b26c606 100644
--- a/src/Support.hs
+++ b/src/Support.hs
@@ -1,85 +1,15 @@
-{-# LANGUAGE DeriveGeneric #-}
+module Support
+  ( module Support
+  , module Support.OrdList
+  , module Support.Rat
+  ) where
 
-module Support where
+import Support.OrdList
+import Support.Rat
 
-import qualified Data.List as List
-import qualified Data.List.Ordered as OrdList
-import GHC.Generics (Generic)
-
-
--- We take some model of the dense linear order. The rationals are a natural
--- choice. (Note that every countable model is order-isomorphic, so it doesn't
--- matter so much in the end.) I wrap it in a newtype, so we will only use the
--- Ord instances, and because it's not very nice to work with type synonyms.
--- Show instance included for debugging.
-newtype Rat = Rat { unRat :: Rational }
-  deriving (Eq, Ord, Show, Generic)
-
--- A support is a set of rational numbers, which can always be ordered. I tried
--- an implementation using Data.Set, it was slower. We could also use Vectors?
--- Note that a sorted list makes sense in many cases, since we do not really
--- need membership queries on this type. Maybe make this into a newtype.
-type Support = [Rat] -- always sorted
-
-size :: Support -> Int
-size = List.length
-
-null :: Support -> Bool
-null = List.null
-
-min :: Support -> Rat
-min = List.head
-
-empty :: Support
-empty = []
-
-union :: Support -> Support -> Support
-union = OrdList.union
-
-singleton :: Rat -> Support
-singleton r = [r]
-
-toList :: Support -> Support
-toList = id
-
-fromList, fromAscList, fromDistinctAscList :: [Rat] -> Support
-fromList = OrdList.nubSort
-fromAscList = OrdList.nub
-fromDistinctAscList = id
+-- A support is a set of rational numbers, which can always be ordered. There
+-- are several implementations: Ordered Lists, Sets, ...? This module chooses
+-- the implementation. Change the import and export to experiment.
 
 def :: Int -> Support
 def n = fromDistinctAscList . fmap (Rat . toRational) $ [1..n]
-
-{-
--- The Data.Set implementation
-import Data.Set (Set)
-import qualified Data.Set as Set
-
-type Support = Set Rat
-
-size :: Support -> Int
-size = Set.size
-
-null :: Support -> Bool
-null = Set.null
-
-min :: Support -> Rat
-min = Set.findMin
-
-empty :: Support
-empty = Set.empty
-
-union :: Support -> Support -> Support
-union = Set.union
-
-singleton :: Rat -> Support
-singleton = Set.singleton
-
-toList :: Support -> [Rat]
-toList = Set.toAscList
-
-fromList, fromAscList, fromDistinctAscList :: [Rat] -> Support
-fromList = Set.fromList
-fromAscList = Set.fromAscList
-fromDistinctAscList = Set.fromDistinctAscList
--}
diff --git a/src/Support/OrdList.hs b/src/Support/OrdList.hs
new file mode 100644
index 0000000..e531ab4
--- /dev/null
+++ b/src/Support/OrdList.hs
@@ -0,0 +1,36 @@
+module Support.OrdList where
+
+import qualified Data.List as List
+import qualified Data.List.Ordered as OrdList
+
+import Support.Rat
+
+-- always sorted
+newtype Support = Support { unSupport :: [Rat] }
+  deriving (Show, Eq, Ord)
+
+size :: Support -> Int
+size = List.length . unSupport
+
+null :: Support -> Bool
+null = List.null . unSupport
+
+min :: Support -> Rat
+min = List.head . unSupport
+
+empty :: Support
+empty = Support []
+
+union :: Support -> Support -> Support
+union (Support x) (Support y) = Support (OrdList.union x y)
+
+singleton :: Rat -> Support
+singleton r = Support [r]
+
+toList :: Support -> [Rat]
+toList = unSupport
+
+fromList, fromAscList, fromDistinctAscList :: [Rat] -> Support
+fromList = Support . OrdList.nubSort
+fromAscList = Support . OrdList.nub
+fromDistinctAscList = Support
diff --git a/src/Support/Rat.hs b/src/Support/Rat.hs
new file mode 100644
index 0000000..bac48ef
--- /dev/null
+++ b/src/Support/Rat.hs
@@ -0,0 +1,13 @@
+{-# LANGUAGE DeriveGeneric #-}
+
+module Support.Rat where
+
+import GHC.Generics (Generic)
+
+-- We take some model of the dense linear order. The rationals are a natural
+-- choice. (Note that every countable model is order-isomorphic, so it doesn't
+-- matter so much in the end.) I wrap it in a newtype, so we will only use the
+-- Ord instances, and because it's not very nice to work with type synonyms.
+-- Show instance included for debugging.
+newtype Rat = Rat { unRat :: Rational }
+  deriving (Eq, Ord, Show, Generic)
diff --git a/src/Support/Set.hs b/src/Support/Set.hs
new file mode 100644
index 0000000..c23647e
--- /dev/null
+++ b/src/Support/Set.hs
@@ -0,0 +1,37 @@
+module Support.Set where
+
+import Data.Set (Set)
+import qualified Data.Set as Set
+
+import Support.Rat
+
+-- Tree-based ordered set
+newtype Support = Support { unSupport :: Set Rat }
+
+size :: Support -> Int
+size = Set.size . unSupport
+
+null :: Support -> Bool
+null = Set.null . unSupport
+
+min :: Support -> Rat
+min = Set.findMin . unSupport
+
+empty :: Support
+empty = Support Set.empty
+
+union :: Support -> Support -> Support
+union (Support x) (Support y) = Support (Set.union x y)
+
+singleton :: Rat -> Support
+singleton = Support . Set.singleton
+
+toList :: Support -> [Rat]
+toList = Set.toAscList . unSupport
+
+fromList, fromAscList, fromDistinctAscList :: [Rat] -> Support
+fromList = Support . Set.fromList
+fromAscList = Support . Set.fromAscList
+fromDistinctAscList = Support . Set.fromDistinctAscList
+
+
diff --git a/stack.yaml b/stack.yaml
index 12a8d61..aaefa01 100644
--- a/stack.yaml
+++ b/stack.yaml
@@ -15,7 +15,7 @@
 # resolver:
 #  name: custom-snapshot
 #  location: "./custom-snapshot.yaml"
-resolver: lts-10.5
+resolver: lts-11.0
 
 # User packages to be built.
 # Various formats can be used as shown in the example below.
@@ -63,4 +63,4 @@ packages:
 # extra-lib-dirs: [/path/to/dir]
 #
 # Allow a newer minor version of GHC than the snapshot specifies
-# compiler-check: newer-minor
\ No newline at end of file
+# compiler-check: newer-minor