diff --git a/Cabal-hooks/Cabal-hooks.cabal b/Cabal-hooks/Cabal-hooks.cabal
index bb6b197cf03..1f50247651e 100644
--- a/Cabal-hooks/Cabal-hooks.cabal
+++ b/Cabal-hooks/Cabal-hooks.cabal
@@ -62,7 +62,6 @@ library
     ScopedTypeVariables
     StandaloneDeriving
     Trustworthy
-    TypeFamilies
     TypeOperators
     TypeSynonymInstances
     UndecidableInstances
diff --git a/Cabal-syntax/Cabal-syntax.cabal b/Cabal-syntax/Cabal-syntax.cabal
index 85137dc147c..18ebca6a390 100644
--- a/Cabal-syntax/Cabal-syntax.cabal
+++ b/Cabal-syntax/Cabal-syntax.cabal
@@ -226,7 +226,6 @@ library
     ScopedTypeVariables
     StandaloneDeriving
     Trustworthy
-    TypeFamilies
     TypeOperators
     TypeSynonymInstances
     UndecidableInstances
diff --git a/Cabal-syntax/src/Distribution/Compat/Graph.hs b/Cabal-syntax/src/Distribution/Compat/Graph.hs
index ea37af99a77..05f3c422a29 100644
--- a/Cabal-syntax/src/Distribution/Compat/Graph.hs
+++ b/Cabal-syntax/src/Distribution/Compat/Graph.hs
@@ -1,8 +1,8 @@
 {-# LANGUAGE BangPatterns #-}
 {-# LANGUAGE FlexibleContexts #-}
+{-# LANGUAGE FlexibleInstances #-}
+{-# LANGUAGE FunctionalDependencies #-}
 {-# LANGUAGE ScopedTypeVariables #-}
-{-# LANGUAGE TypeFamilies #-}
-{-# LANGUAGE TypeOperators #-}
 {-# LANGUAGE UndecidableInstances #-}
 
 -- |
@@ -107,40 +107,40 @@ import qualified Distribution.Compat.Prelude as Prelude
 
 -- | A graph of nodes @a@.  The nodes are expected to have instance
 -- of class 'IsNode'.
-data Graph a = Graph
-  { graphMap :: !(Map (Key a) a)
+data Graph keyA a = Graph
+  { graphMap :: !(Map keyA a)
   , -- Lazily cached graph representation
     graphForward :: G.Graph
   , graphAdjoint :: G.Graph
   , graphVertexToNode :: G.Vertex -> a
-  , graphKeyToVertex :: Key a -> Maybe G.Vertex
-  , graphBroken :: [(a, [Key a])]
+  , graphKeyToVertex :: keyA -> Maybe G.Vertex
+  , graphBroken :: [(a, [keyA])]
   }
 
 -- NB: Not a Functor! (or Traversable), because you need
--- to restrict Key a ~ Key b.  We provide our own mapping
+-- to restrict keyA ~ Key b.  We provide our own mapping
 -- functions.
 
 -- General strategy is most operations are deferred to the
 -- Map representation.
 
-instance Show a => Show (Graph a) where
+instance Show a => Show (Graph keyA a) where
   show = show . toList
 
-instance (IsNode a, Read a, Show (Key a)) => Read (Graph a) where
+instance (IsNode keyA a, Read a, Show keyA) => Read (Graph keyA a) where
   readsPrec d s = map (first fromDistinctList) (readsPrec d s)
 
-instance (IsNode a, Binary a, Show (Key a)) => Binary (Graph a) where
+instance (IsNode keyA a, Binary a, Show keyA) => Binary (Graph keyA a) where
   put x = put (toList x)
   get = fmap fromDistinctList get
 
-instance Structured a => Structured (Graph a) where
+instance (Structured a, Typeable keyA) => Structured (Graph keyA a) where
   structure p = Nominal (typeRep p) 0 "Graph" [structure (Proxy :: Proxy a)]
 
-instance (Eq (Key a), Eq a) => Eq (Graph a) where
+instance (Eq keyA, Eq a) => Eq (Graph keyA a) where
   g1 == g2 = graphMap g1 == graphMap g2
 
-instance Foldable.Foldable Graph where
+instance Foldable.Foldable (Graph keyA) where
   elem x = Foldable.elem x . graphMap
   fold = Foldable.fold . graphMap
   foldl f z = Foldable.foldl f z . graphMap
@@ -156,7 +156,7 @@ instance Foldable.Foldable Graph where
   sum = Foldable.sum . graphMap
   toList = Foldable.toList . graphMap
 
-instance (NFData a, NFData (Key a)) => NFData (Graph a) where
+instance (NFData a, NFData keyA) => NFData (Graph keyA a) where
   rnf
     Graph
       { graphMap = m
@@ -173,13 +173,11 @@ instance (NFData a, NFData (Key a)) => NFData (Graph a) where
 -- graph nodes.  A node of type @a@ is associated with some unique key of
 -- type @'Key' a@; given a node we can determine its key ('nodeKey')
 -- and the keys of its neighbors ('nodeNeighbors').
-class Ord (Key a) => IsNode a where
-  type Key a
-  nodeKey :: a -> Key a
-  nodeNeighbors :: a -> [Key a]
+class Ord keyA => IsNode keyA a | a -> keyA where
+  nodeKey :: a -> keyA
+  nodeNeighbors :: a -> [keyA]
 
-instance (IsNode a, IsNode b, Key a ~ Key b) => IsNode (Either a b) where
-  type Key (Either a b) = Key a
+instance (IsNode key a, IsNode key b) => IsNode key (Either a b) where
   nodeKey (Left x) = nodeKey x
   nodeKey (Right x) = nodeKey x
   nodeNeighbors (Left x) = nodeNeighbors x
@@ -196,50 +194,49 @@ nodeValue (N a _ _) = a
 instance Functor (Node k) where
   fmap f (N a k ks) = N (f a) k ks
 
-instance Ord k => IsNode (Node k a) where
-  type Key (Node k a) = k
+instance Ord k => IsNode k (Node k a) where
   nodeKey (N _ k _) = k
   nodeNeighbors (N _ _ ks) = ks
 
 -- TODO: Maybe introduce a typeclass for items which just
--- keys (so, Key associated type, and nodeKey method).  But
+-- keys (so, keyAssociated type, and nodeKey method).  But
 -- I didn't need it here, so I didn't introduce it.
 
 -- Query
 
 -- | /O(1)/. Is the graph empty?
-null :: Graph a -> Bool
+null :: Graph keyA a -> Bool
 null = Map.null . toMap
 
 -- | /O(1)/. The number of nodes in the graph.
-size :: Graph a -> Int
+size :: Graph keyA a -> Int
 size = Map.size . toMap
 
 -- | /O(log V)/. Check if the key is in the graph.
-member :: IsNode a => Key a -> Graph a -> Bool
+member :: IsNode keyA a => keyA -> Graph keyA a -> Bool
 member k g = Map.member k (toMap g)
 
 -- | /O(log V)/. Lookup the node at a key in the graph.
-lookup :: IsNode a => Key a -> Graph a -> Maybe a
+lookup :: IsNode keyA a => keyA -> Graph keyA a -> Maybe a
 lookup k g = Map.lookup k (toMap g)
 
 -- Construction
 
 -- | /O(1)/. The empty graph.
-empty :: IsNode a => Graph a
+empty :: IsNode keyA a => Graph keyA a
 empty = fromMap Map.empty
 
 -- | /O(log V)/. Insert a node into a graph.
-insert :: IsNode a => a -> Graph a -> Graph a
+insert :: IsNode keyA a => a -> Graph keyA a -> Graph keyA a
 insert !n g = fromMap (Map.insert (nodeKey n) n (toMap g))
 
 -- | /O(log V)/. Delete the node at a key from the graph.
-deleteKey :: IsNode a => Key a -> Graph a -> Graph a
+deleteKey :: IsNode keyA a => keyA -> Graph keyA a -> Graph keyA a
 deleteKey k g = fromMap (Map.delete k (toMap g))
 
 -- | /O(log V)/. Lookup and delete.  This function returns the deleted
 -- value if it existed.
-deleteLookup :: IsNode a => Key a -> Graph a -> (Maybe a, Graph a)
+deleteLookup :: IsNode keyA a => keyA -> Graph keyA a -> (Maybe a, Graph keyA a)
 deleteLookup k g =
   let (r, m') = Map.updateLookupWithKey (\_ _ -> Nothing) k (toMap g)
    in (r, fromMap m')
@@ -249,19 +246,19 @@ deleteLookup k g =
 -- | /O(V + V')/. Right-biased union, preferring entries
 -- from the second map when conflicts occur.
 -- @'nodeKey' x = 'nodeKey' (f x)@.
-unionRight :: IsNode a => Graph a -> Graph a -> Graph a
+unionRight :: IsNode keyA a => Graph keyA a -> Graph keyA a -> Graph keyA a
 unionRight g g' = fromMap (Map.union (toMap g') (toMap g))
 
 -- | /O(V + V')/. Left-biased union, preferring entries from
 -- the first map when conflicts occur.
-unionLeft :: IsNode a => Graph a -> Graph a -> Graph a
+unionLeft :: IsNode keyA a => Graph keyA a -> Graph keyA a -> Graph keyA a
 unionLeft = flip unionRight
 
 -- Graph-like operations
 
 -- | /Ω(V + E)/. Compute the strongly connected components of a graph.
 -- Requires amortized construction of graph.
-stronglyConnComp :: Graph a -> [SCC a]
+stronglyConnComp :: Graph keyA a -> [SCC a]
 stronglyConnComp g = map decode forest
   where
     forest = G.scc (graphForward g)
@@ -278,25 +275,25 @@ stronglyConnComp g = map decode forest
 
 -- | /Ω(V + E)/. Compute the cycles of a graph.
 -- Requires amortized construction of graph.
-cycles :: Graph a -> [[a]]
+cycles :: Graph keyA a -> [[a]]
 cycles g = [vs | CyclicSCC vs <- stronglyConnComp g]
 
 -- | /O(1)/.  Return a list of nodes paired with their broken
 -- neighbors (i.e., neighbor keys which are not in the graph).
 -- Requires amortized construction of graph.
-broken :: Graph a -> [(a, [Key a])]
+broken :: Graph keyA a -> [(a, [keyA])]
 broken g = graphBroken g
 
 -- | Lookup the immediate neighbors from a key in the graph.
 -- Requires amortized construction of graph.
-neighbors :: Graph a -> Key a -> Maybe [a]
+neighbors :: Graph keyA a -> keyA -> Maybe [a]
 neighbors g k = do
   v <- graphKeyToVertex g k
   return (map (graphVertexToNode g) (graphForward g ! v))
 
 -- | Lookup the immediate reverse neighbors from a key in the graph.
 -- Requires amortized construction of graph.
-revNeighbors :: Graph a -> Key a -> Maybe [a]
+revNeighbors :: Graph keyA a -> keyA -> Maybe [a]
 revNeighbors g k = do
   v <- graphKeyToVertex g k
   return (map (graphVertexToNode g) (graphAdjoint g ! v))
@@ -305,7 +302,7 @@ revNeighbors g k = do
 -- Returns @Nothing@ if one (or more) keys are not present in
 -- the graph.
 -- Requires amortized construction of graph.
-closure :: Graph a -> [Key a] -> Maybe [a]
+closure :: Graph keyA a -> [keyA] -> Maybe [a]
 closure g ks = do
   vs <- traverse (graphKeyToVertex g) ks
   return (decodeVertexForest g (G.dfs (graphForward g) vs))
@@ -314,7 +311,7 @@ closure g ks = do
 -- of keys.  Returns @Nothing@ if one (or more) keys are not present in
 -- the graph.
 -- Requires amortized construction of graph.
-revClosure :: Graph a -> [Key a] -> Maybe [a]
+revClosure :: Graph keyA a -> [keyA] -> Maybe [a]
 revClosure g ks = do
   vs <- traverse (graphKeyToVertex g) ks
   return (decodeVertexForest g (G.dfs (graphAdjoint g) vs))
@@ -322,17 +319,17 @@ revClosure g ks = do
 flattenForest :: Tree.Forest a -> [a]
 flattenForest = concatMap Tree.flatten
 
-decodeVertexForest :: Graph a -> Tree.Forest G.Vertex -> [a]
+decodeVertexForest :: Graph keyA a -> Tree.Forest G.Vertex -> [a]
 decodeVertexForest g = map (graphVertexToNode g) . flattenForest
 
 -- | Topologically sort the nodes of a graph.
 -- Requires amortized construction of graph.
-topSort :: Graph a -> [a]
+topSort :: Graph keyA a -> [a]
 topSort g = map (graphVertexToNode g) $ G.topSort (graphForward g)
 
 -- | Reverse topologically sort the nodes of a graph.
 -- Requires amortized construction of graph.
-revTopSort :: Graph a -> [a]
+revTopSort :: Graph keyA a -> [a]
 revTopSort g = map (graphVertexToNode g) $ G.topSort (graphAdjoint g)
 
 -- Conversions
@@ -343,7 +340,7 @@ revTopSort g = map (graphVertexToNode g) $ G.topSort (graphAdjoint g)
 -- if you can't fulfill this invariant use @'fromList' ('Data.Map.elems' m)@
 -- instead.  The values of the map are assumed to already
 -- be in WHNF.
-fromMap :: IsNode a => Map (Key a) a -> Graph a
+fromMap :: IsNode keyA a => Map keyA a -> Graph keyA a
 fromMap m =
   Graph
     { graphMap = m
@@ -377,7 +374,7 @@ fromMap m =
     bounds = (0, Map.size m - 1)
 
 -- | /O(V log V)/. Convert a list of nodes (with distinct keys) into a graph.
-fromDistinctList :: (IsNode a, Show (Key a)) => [a] -> Graph a
+fromDistinctList :: (IsNode keyA a, Show keyA) => [a] -> Graph keyA a
 fromDistinctList =
   fromMap
     . Map.fromListWith (\_ -> duplicateError)
@@ -391,26 +388,26 @@ fromDistinctList =
 -- Map-like operations
 
 -- | /O(V)/. Convert a graph into a list of nodes.
-toList :: Graph a -> [a]
+toList :: Graph keyA a -> [a]
 toList g = Map.elems (toMap g)
 
 -- | /O(V)/. Convert a graph into a list of keys.
-keys :: Graph a -> [Key a]
+keys :: Graph keyA a -> [keyA]
 keys g = Map.keys (toMap g)
 
 -- | /O(V)/. Convert a graph into a set of keys.
-keysSet :: Graph a -> Set.Set (Key a)
+keysSet :: Graph keyA a -> Set.Set keyA
 keysSet g = Map.keysSet (toMap g)
 
 -- | /O(1)/. Convert a graph into a map from keys to nodes.
 -- The resulting map @m@ is guaranteed to have the property that
 -- @'Prelude.all' (\(k,n) -> k == 'nodeKey' n) ('Data.Map.toList' m)@.
-toMap :: Graph a -> Map (Key a) a
+toMap :: Graph keyA a -> Map keyA a
 toMap = graphMap
 
 -- Graph-like operations
 
 -- | /O(1)/. Convert a graph into a 'Data.Graph.Graph'.
 -- Requires amortized construction of graph.
-toGraph :: Graph a -> (G.Graph, G.Vertex -> a, Key a -> Maybe G.Vertex)
+toGraph :: Graph keyA a -> (G.Graph, G.Vertex -> a, keyA -> Maybe G.Vertex)
 toGraph g = (graphForward g, graphVertexToNode g, graphKeyToVertex g)
diff --git a/Cabal-syntax/src/Distribution/Types/InstalledPackageInfo.hs b/Cabal-syntax/src/Distribution/Types/InstalledPackageInfo.hs
index f57457d2e5b..d92c8aa14e1 100644
--- a/Cabal-syntax/src/Distribution/Types/InstalledPackageInfo.hs
+++ b/Cabal-syntax/src/Distribution/Types/InstalledPackageInfo.hs
@@ -1,6 +1,6 @@
 {-# LANGUAGE DeriveGeneric #-}
+{-# LANGUAGE MultiParamTypeClasses #-}
 {-# LANGUAGE OverloadedStrings #-}
-{-# LANGUAGE TypeFamilies #-}
 
 module Distribution.Types.InstalledPackageInfo
   ( InstalledPackageInfo (..)
@@ -113,8 +113,7 @@ instance Package.HasUnitId InstalledPackageInfo where
 instance Package.PackageInstalled InstalledPackageInfo where
   installedDepends = depends
 
-instance IsNode InstalledPackageInfo where
-  type Key InstalledPackageInfo = UnitId
+instance IsNode UnitId InstalledPackageInfo where
   nodeKey = installedUnitId
   nodeNeighbors = depends
 
diff --git a/Cabal-syntax/src/Distribution/Utils/Path.hs b/Cabal-syntax/src/Distribution/Utils/Path.hs
index a4d09334e01..64e7a0ee2c3 100644
--- a/Cabal-syntax/src/Distribution/Utils/Path.hs
+++ b/Cabal-syntax/src/Distribution/Utils/Path.hs
@@ -3,9 +3,10 @@
 {-# LANGUAGE DeriveGeneric #-}
 {-# LANGUAGE FlexibleInstances #-}
 {-# LANGUAGE FunctionalDependencies #-}
+{-# LANGUAGE GADTs #-}
+{-# LANGUAGE KindSignatures #-}
 {-# LANGUAGE RankNTypes #-}
 {-# LANGUAGE RoleAnnotations #-}
-{-# LANGUAGE TypeFamilies #-}
 {-# LANGUAGE TypeOperators #-}
 {-# LANGUAGE UndecidableInstances #-}
 
diff --git a/Cabal-syntax/src/Distribution/Utils/Structured.hs b/Cabal-syntax/src/Distribution/Utils/Structured.hs
index b88165a89bb..c035b1e67e8 100644
--- a/Cabal-syntax/src/Distribution/Utils/Structured.hs
+++ b/Cabal-syntax/src/Distribution/Utils/Structured.hs
@@ -2,10 +2,10 @@
 {-# LANGUAGE DefaultSignatures #-}
 {-# LANGUAGE DeriveGeneric #-}
 {-# LANGUAGE FlexibleContexts #-}
+{-# LANGUAGE GADTs #-}
 {-# LANGUAGE PolyKinds #-}
 {-# LANGUAGE ScopedTypeVariables #-}
 {-# LANGUAGE TypeApplications #-}
-{-# LANGUAGE TypeFamilies #-}
 {-# LANGUAGE TypeOperators #-}
 
 -- |
diff --git a/Cabal-tests/tests/UnitTests/Distribution/Compat/Graph.hs b/Cabal-tests/tests/UnitTests/Distribution/Compat/Graph.hs
index 0e2ea86318b..e4ebb225f0d 100644
--- a/Cabal-tests/tests/UnitTests/Distribution/Compat/Graph.hs
+++ b/Cabal-tests/tests/UnitTests/Distribution/Compat/Graph.hs
@@ -21,20 +21,20 @@ import Data.List (sort)
 
 tests :: [TestTree]
 tests =
-    [ testProperty "arbitrary unbroken" (prop_arbitrary_unbroken :: Graph (Node Int ()) -> Bool)
-    , testProperty "nodes consistent" (prop_nodes_consistent :: Graph (Node Int ()) -> Bool)
-    , testProperty "edges consistent" (prop_edges_consistent :: Graph (Node Int ()) -> Property)
-    , testProperty "closure consistent" (prop_closure_consistent :: Graph (Node Int ()) -> Property)
+    [ testProperty "arbitrary unbroken" (prop_arbitrary_unbroken :: Graph Int (Node Int ()) -> Bool)
+    , testProperty "nodes consistent" (prop_nodes_consistent :: Graph Int (Node Int ()) -> Bool)
+    , testProperty "edges consistent" (prop_edges_consistent :: Graph Int (Node Int ()) -> Property)
+    , testProperty "closure consistent" (prop_closure_consistent :: Graph Int (Node Int ()) -> Property)
     ]
 
 -- Our arbitrary instance does not generate broken graphs
-prop_arbitrary_unbroken :: Graph a -> Bool
+prop_arbitrary_unbroken :: Graph keyA a -> Bool
 prop_arbitrary_unbroken g = Prelude.null (broken g)
 
 -- Every node from 'toList' maps to a vertex which
 -- is present in the constructed graph, and maps back
 -- to a node correctly.
-prop_nodes_consistent :: (Eq a, IsNode a) => Graph a -> Bool
+prop_nodes_consistent :: (Eq a, IsNode keyA a) => Graph keyA a -> Bool
 prop_nodes_consistent g = all p (toList g)
   where
     (_, vtn, ktv) = toGraph g
@@ -44,7 +44,7 @@ prop_nodes_consistent g = all p (toList g)
 
 -- A non-broken graph has the 'nodeNeighbors' of each node
 -- equal the recorded adjacent edges in the node graph.
-prop_edges_consistent :: IsNode a => Graph a -> Property
+prop_edges_consistent :: IsNode keyA a => Graph keyA a -> Property
 prop_edges_consistent g = Prelude.null (broken g) ==> all p (toList g)
   where
     (gr, vtn, ktv) = toGraph g
@@ -52,7 +52,7 @@ prop_edges_consistent g = Prelude.null (broken g) ==> all p (toList g)
        == sort (map (nodeKey . vtn) (gr ! fromJust (ktv (nodeKey n))))
 
 -- Closure is consistent with reachable
-prop_closure_consistent :: (Show a, IsNode a) => Graph a -> Property
+prop_closure_consistent :: (Show a, IsNode keyA a) => Graph keyA a -> Property
 prop_closure_consistent g =
     not (null g) ==>
     forAll (elements (toList g)) $ \n ->
@@ -73,7 +73,7 @@ hasNoDups = loop Set.empty
 -- | Produces a graph of size @len@.  We sample with 'suchThat'; if we
 -- dropped duplicate entries our size could be smaller.
 arbitraryGraph :: (Ord k, Show k, Arbitrary k, Arbitrary a)
-               => Int -> Gen (Graph (Node k a))
+               => Int -> Gen (Graph k (Node k a))
 arbitraryGraph len = do
     -- Careful! Assume k is much larger than size.
     ks <- vectorOf len arbitrary `suchThat` hasNoDups
@@ -85,7 +85,7 @@ arbitraryGraph len = do
     return (fromDistinctList ns)
 
 instance (Ord k, Show k, Arbitrary k, Arbitrary a)
-      => Arbitrary (Graph (Node k a)) where
+      => Arbitrary (Graph k (Node k a)) where
     arbitrary = sized $ \n -> do
         len <- choose (0, n)
         arbitraryGraph len
diff --git a/Cabal/Cabal.cabal b/Cabal/Cabal.cabal
index 647cb5f1523..558361e4227 100644
--- a/Cabal/Cabal.cabal
+++ b/Cabal/Cabal.cabal
@@ -413,7 +413,6 @@ library
     ScopedTypeVariables
     StandaloneDeriving
     Trustworthy
-    TypeFamilies
     TypeOperators
     TypeSynonymInstances
     UndecidableInstances
diff --git a/Cabal/src/Distribution/Backpack/ComponentsGraph.hs b/Cabal/src/Distribution/Backpack/ComponentsGraph.hs
index aef3db817c6..5e8e1be66d5 100644
--- a/Cabal/src/Distribution/Backpack/ComponentsGraph.hs
+++ b/Cabal/src/Distribution/Backpack/ComponentsGraph.hs
@@ -30,7 +30,7 @@ import Text.PrettyPrint
 
 -- | A graph of source-level components by their source-level
 -- dependencies
-type ComponentsGraph = Graph (Node ComponentName Component)
+type ComponentsGraph = Graph ComponentName (Node ComponentName Component)
 
 -- | A list of components associated with the source level
 -- dependencies between them.
diff --git a/Cabal/src/Distribution/Backpack/Configure.hs b/Cabal/src/Distribution/Backpack/Configure.hs
index 55d1ae03254..dedc12f7e69 100644
--- a/Cabal/src/Distribution/Backpack/Configure.hs
+++ b/Cabal/src/Distribution/Backpack/Configure.hs
@@ -2,7 +2,6 @@
 {-# LANGUAGE OverloadedStrings #-}
 {-# LANGUAGE PatternGuards #-}
 {-# LANGUAGE ScopedTypeVariables #-}
-{-# LANGUAGE TypeFamilies #-}
 {-# LANGUAGE NoMonoLocalBinds #-}
 
 -- | See <https://github.com/ezyang/ghc-proposals/blob/backpack/proposals/0000-backpack.rst>
@@ -232,12 +231,12 @@ toComponentLocalBuildInfos
       -- since we will pay for the ALL installed packages even if
       -- they are not related to what we are building.  This was true
       -- in the old configure code.
-      external_graph :: Graph (Either InstalledPackageInfo ReadyComponent)
+      external_graph :: Graph UnitId (Either InstalledPackageInfo ReadyComponent)
       external_graph =
         Graph.fromDistinctList
           . map Left
           $ PackageIndex.allPackages installedPackageSet
-      internal_graph :: Graph (Either InstalledPackageInfo ReadyComponent)
+      internal_graph :: Graph UnitId (Either InstalledPackageInfo ReadyComponent)
       internal_graph =
         Graph.fromDistinctList
           . map Right
diff --git a/Cabal/src/Distribution/Backpack/LinkedComponent.hs b/Cabal/src/Distribution/Backpack/LinkedComponent.hs
index b2d2bc25066..782e5659bca 100644
--- a/Cabal/src/Distribution/Backpack/LinkedComponent.hs
+++ b/Cabal/src/Distribution/Backpack/LinkedComponent.hs
@@ -1,5 +1,4 @@
 {-# LANGUAGE ScopedTypeVariables #-}
-{-# LANGUAGE TypeFamilies #-}
 
 -- | See <https://github.com/ezyang/ghc-proposals/blob/backpack/proposals/0000-backpack.rst>
 module Distribution.Backpack.LinkedComponent
diff --git a/Cabal/src/Distribution/Backpack/ReadyComponent.hs b/Cabal/src/Distribution/Backpack/ReadyComponent.hs
index 3eef45fadbb..a87f456dfd0 100644
--- a/Cabal/src/Distribution/Backpack/ReadyComponent.hs
+++ b/Cabal/src/Distribution/Backpack/ReadyComponent.hs
@@ -1,6 +1,6 @@
+{-# LANGUAGE MultiParamTypeClasses #-}
 {-# LANGUAGE PatternGuards #-}
 {-# LANGUAGE TupleSections #-}
-{-# LANGUAGE TypeFamilies #-}
 
 -- | See <https://github.com/ezyang/ghc-proposals/blob/backpack/proposals/0000-backpack.rst>
 module Distribution.Backpack.ReadyComponent
@@ -164,8 +164,7 @@ instance Package ReadyComponent where
 instance HasUnitId ReadyComponent where
   installedUnitId = rc_uid
 
-instance IsNode ReadyComponent where
-  type Key ReadyComponent = UnitId
+instance IsNode UnitId ReadyComponent where
   nodeKey = rc_uid
   nodeNeighbors rc =
     ( case rc_i rc of
diff --git a/Cabal/src/Distribution/Types/ComponentLocalBuildInfo.hs b/Cabal/src/Distribution/Types/ComponentLocalBuildInfo.hs
index 32f4aab473b..6eb88680479 100644
--- a/Cabal/src/Distribution/Types/ComponentLocalBuildInfo.hs
+++ b/Cabal/src/Distribution/Types/ComponentLocalBuildInfo.hs
@@ -1,5 +1,5 @@
 {-# LANGUAGE DeriveGeneric #-}
-{-# LANGUAGE TypeFamilies #-}
+{-# LANGUAGE MultiParamTypeClasses #-}
 
 module Distribution.Types.ComponentLocalBuildInfo
   ( ComponentLocalBuildInfo (..)
@@ -114,8 +114,7 @@ data ComponentLocalBuildInfo
 instance Binary ComponentLocalBuildInfo
 instance Structured ComponentLocalBuildInfo
 
-instance IsNode ComponentLocalBuildInfo where
-  type Key ComponentLocalBuildInfo = UnitId
+instance IsNode UnitId ComponentLocalBuildInfo where
   nodeKey = componentUnitId
   nodeNeighbors = componentInternalDeps
 
diff --git a/Cabal/src/Distribution/Types/LocalBuildConfig.hs b/Cabal/src/Distribution/Types/LocalBuildConfig.hs
index 12648a8357b..dc1349bb28d 100644
--- a/Cabal/src/Distribution/Types/LocalBuildConfig.hs
+++ b/Cabal/src/Distribution/Types/LocalBuildConfig.hs
@@ -89,7 +89,7 @@ data PackageBuildDescr = PackageBuildDescr
 -- | Information about individual components in a package,
 -- determined after the configure step.
 data ComponentBuildDescr = ComponentBuildDescr
-  { componentGraph :: Graph ComponentLocalBuildInfo
+  { componentGraph :: Graph UnitId ComponentLocalBuildInfo
   -- ^ All the components to build, ordered by topological
   -- sort, and with their INTERNAL dependencies over the
   -- intrapackage dependency graph.
diff --git a/Cabal/src/Distribution/Types/LocalBuildInfo.hs b/Cabal/src/Distribution/Types/LocalBuildInfo.hs
index 854f454dc87..28008e3b8b4 100644
--- a/Cabal/src/Distribution/Types/LocalBuildInfo.hs
+++ b/Cabal/src/Distribution/Types/LocalBuildInfo.hs
@@ -158,7 +158,7 @@ pattern LocalBuildInfo
   -> Compiler
   -> Platform
   -> Maybe (SymbolicPath Pkg File)
-  -> Graph ComponentLocalBuildInfo
+  -> Graph UnitId ComponentLocalBuildInfo
   -> Map ComponentName [ComponentLocalBuildInfo]
   -> Map (PackageName, ComponentName) PromisedComponent
   -> InstalledPackageIndex
diff --git a/Cabal/src/Distribution/Types/TargetInfo.hs b/Cabal/src/Distribution/Types/TargetInfo.hs
index a743b0b21b0..7bb1b3e5071 100644
--- a/Cabal/src/Distribution/Types/TargetInfo.hs
+++ b/Cabal/src/Distribution/Types/TargetInfo.hs
@@ -1,5 +1,5 @@
 {-# LANGUAGE DeriveGeneric #-}
-{-# LANGUAGE TypeFamilies #-}
+{-# LANGUAGE MultiParamTypeClasses #-}
 
 module Distribution.Types.TargetInfo
   ( TargetInfo (..)
@@ -33,7 +33,6 @@ data TargetInfo = TargetInfo
 instance Binary TargetInfo
 instance Structured TargetInfo
 
-instance IsNode TargetInfo where
-  type Key TargetInfo = UnitId
+instance IsNode UnitId TargetInfo where
   nodeKey = nodeKey . targetCLBI
   nodeNeighbors = nodeNeighbors . targetCLBI
diff --git a/cabal-install-solver/src/Distribution/Solver/Modular/Cycles.hs b/cabal-install-solver/src/Distribution/Solver/Modular/Cycles.hs
index b82e39a0d26..d537e2388fb 100644
--- a/cabal-install-solver/src/Distribution/Solver/Modular/Cycles.hs
+++ b/cabal-install-solver/src/Distribution/Solver/Modular/Cycles.hs
@@ -1,4 +1,5 @@
-{-# LANGUAGE TypeFamilies #-}
+{-# LANGUAGE FlexibleInstances #-}
+{-# LANGUAGE MultiParamTypeClasses #-}
 module Distribution.Solver.Modular.Cycles (
     detectCyclesPhase
   ) where
@@ -71,7 +72,7 @@ findCycles pkg rdm =
     -- strongly connected component.
     --
     if hasCycle
-    then let scc :: G.Graph RevDepMapNode
+    then let scc :: G.Graph QPN RevDepMapNode
              scc = case G.cycles $ revDepMapToGraph rdm of
                      []    -> findCyclesError "cannot find a strongly connected component"
                      c : _ -> G.fromDistinctList c
@@ -110,11 +111,10 @@ findCycles pkg rdm =
 
 data RevDepMapNode = RevDepMapNode QPN [(Component, QPN)]
 
-instance G.IsNode RevDepMapNode where
-  type Key RevDepMapNode = QPN
+instance G.IsNode QPN RevDepMapNode where
   nodeKey (RevDepMapNode qpn _) = qpn
   nodeNeighbors (RevDepMapNode _ ns) = ordNub $ map snd ns
 
-revDepMapToGraph :: RevDepMap -> G.Graph RevDepMapNode
+revDepMapToGraph :: RevDepMap -> G.Graph QPN RevDepMapNode
 revDepMapToGraph rdm = G.fromDistinctList
                        [RevDepMapNode qpn ns | (qpn, ns) <- M.toList rdm]
diff --git a/cabal-install-solver/src/Distribution/Solver/Types/ResolverPackage.hs b/cabal-install-solver/src/Distribution/Solver/Types/ResolverPackage.hs
index 840e58aff94..44a9960877b 100644
--- a/cabal-install-solver/src/Distribution/Solver/Types/ResolverPackage.hs
+++ b/cabal-install-solver/src/Distribution/Solver/Types/ResolverPackage.hs
@@ -1,4 +1,4 @@
-{-# LANGUAGE TypeFamilies #-}
+{-# LANGUAGE MultiParamTypeClasses #-}
 {-# LANGUAGE DeriveGeneric #-}
 module Distribution.Solver.Types.ResolverPackage
     ( ResolverPackage(..)
@@ -42,8 +42,7 @@ resolverPackageExeDeps :: ResolverPackage loc -> CD.ComponentDeps [SolverId]
 resolverPackageExeDeps (PreExisting ipkg) = instSolverPkgExeDeps ipkg
 resolverPackageExeDeps (Configured spkg) = solverPkgExeDeps spkg
 
-instance IsNode (ResolverPackage loc) where
-  type Key (ResolverPackage loc) = SolverId
+instance IsNode SolverId (ResolverPackage loc) where
   nodeKey (PreExisting ipkg) = PreExistingId (packageId ipkg) (installedUnitId ipkg)
   nodeKey (Configured spkg) = PlannedId (packageId spkg)
   -- Use dependencies for ALL components
diff --git a/cabal-install/src/Distribution/Client/Dependency.hs b/cabal-install/src/Distribution/Client/Dependency.hs
index a65c41cb046..e18c855f53e 100644
--- a/cabal-install/src/Distribution/Client/Dependency.hs
+++ b/cabal-install/src/Distribution/Client/Dependency.hs
@@ -943,7 +943,7 @@ validateSolverResult platform comp indepGoals pkgs =
       Left problems -> error (formatPlanProblems problems)
     problems -> error (formatPkgProblems problems)
   where
-    graph :: Graph.Graph (ResolverPackage UnresolvedPkgLoc)
+    graph :: Graph.Graph SolverId (ResolverPackage UnresolvedPkgLoc)
     graph = Graph.fromDistinctList pkgs
 
     formatPkgProblems :: [PlanPackageProblem] -> String
diff --git a/cabal-install/src/Distribution/Client/InstallPlan.hs b/cabal-install/src/Distribution/Client/InstallPlan.hs
index 671617d2726..72c5146ec1b 100644
--- a/cabal-install/src/Distribution/Client/InstallPlan.hs
+++ b/cabal-install/src/Distribution/Client/InstallPlan.hs
@@ -2,12 +2,8 @@
 {-# LANGUAGE ConstraintKinds #-}
 {-# LANGUAGE DeriveGeneric #-}
 {-# LANGUAGE FlexibleContexts #-}
+{-# LANGUAGE MultiParamTypeClasses #-}
 {-# LANGUAGE ScopedTypeVariables #-}
-{-# LANGUAGE TypeFamilies #-}
-
------------------------------------------------------------------------------
-
------------------------------------------------------------------------------
 
 -- |
 -- Module      :  Distribution.Client.InstallPlan
@@ -193,7 +189,7 @@ foldPlanPackage f _ (PreExisting ipkg) = f ipkg
 foldPlanPackage _ g (Configured srcpkg) = g srcpkg
 foldPlanPackage _ g (Installed srcpkg) = g srcpkg
 
-type IsUnit a = (IsNode a, Key a ~ UnitId)
+type IsUnit a = IsNode UnitId a
 
 depends :: IsUnit a => a -> [UnitId]
 depends = nodeNeighbors
@@ -201,10 +197,9 @@ depends = nodeNeighbors
 -- NB: Expanded constraint synonym here to avoid undecidable
 -- instance errors in GHC 7.8 and earlier.
 instance
-  (IsNode ipkg, IsNode srcpkg, Key ipkg ~ UnitId, Key srcpkg ~ UnitId)
-  => IsNode (GenericPlanPackage ipkg srcpkg)
+  (IsNode UnitId ipkg, IsNode UnitId srcpkg)
+  => IsNode UnitId (GenericPlanPackage ipkg srcpkg)
   where
-  type Key (GenericPlanPackage ipkg srcpkg) = UnitId
   nodeKey (PreExisting ipkg) = nodeKey ipkg
   nodeKey (Configured spkg) = nodeKey spkg
   nodeKey (Installed spkg) = nodeKey spkg
@@ -254,7 +249,7 @@ instance
   configuredId (Installed spkg) = configuredId spkg
 
 data GenericInstallPlan ipkg srcpkg = GenericInstallPlan
-  { planGraph :: !(Graph (GenericPlanPackage ipkg srcpkg))
+  { planGraph :: !(Graph UnitId (GenericPlanPackage ipkg srcpkg))
   , planIndepGoals :: !IndependentGoals
   }
 
@@ -268,7 +263,7 @@ type InstallPlan =
 mkInstallPlan
   :: (IsUnit ipkg, IsUnit srcpkg)
   => String
-  -> Graph (GenericPlanPackage ipkg srcpkg)
+  -> Graph UnitId (GenericPlanPackage ipkg srcpkg)
   -> IndependentGoals
   -> GenericInstallPlan ipkg srcpkg
 mkInstallPlan loc graph indepGoals =
@@ -297,10 +292,8 @@ instance (Structured ipkg, Structured srcpkg) => Structured (GenericInstallPlan
       ]
 
 instance
-  ( IsNode ipkg
-  , Key ipkg ~ UnitId
-  , IsNode srcpkg
-  , Key srcpkg ~ UnitId
+  ( IsNode UnitId ipkg
+  , IsNode UnitId srcpkg
   , Binary ipkg
   , Binary srcpkg
   )
@@ -365,13 +358,13 @@ showPlanPackageTag (Installed _) = "Installed"
 new
   :: (IsUnit ipkg, IsUnit srcpkg)
   => IndependentGoals
-  -> Graph (GenericPlanPackage ipkg srcpkg)
+  -> Graph UnitId (GenericPlanPackage ipkg srcpkg)
   -> GenericInstallPlan ipkg srcpkg
 new indepGoals graph = mkInstallPlan "new" graph indepGoals
 
 toGraph
   :: GenericInstallPlan ipkg srcpkg
-  -> Graph (GenericPlanPackage ipkg srcpkg)
+  -> Graph UnitId (GenericPlanPackage ipkg srcpkg)
 toGraph = planGraph
 
 toList
@@ -1004,7 +997,7 @@ execute jobCtl keepGoing depFailure plan installPkg =
 valid
   :: (IsUnit ipkg, IsUnit srcpkg)
   => String
-  -> Graph (GenericPlanPackage ipkg srcpkg)
+  -> Graph UnitId (GenericPlanPackage ipkg srcpkg)
   -> Bool
 valid loc graph =
   case problems graph of
@@ -1046,7 +1039,7 @@ showPlanProblem (PackageStateInvalid pkg pkg') =
 -- Use 'showPlanProblem' for a human readable explanation.
 problems
   :: (IsUnit ipkg, IsUnit srcpkg)
-  => Graph (GenericPlanPackage ipkg srcpkg)
+  => Graph UnitId (GenericPlanPackage ipkg srcpkg)
   -> [PlanProblem ipkg srcpkg]
 problems graph =
   [ PackageMissingDeps
diff --git a/cabal-install/src/Distribution/Client/ProjectBuilding.hs b/cabal-install/src/Distribution/Client/ProjectBuilding.hs
index 7bf6de869a5..cc69e804722 100644
--- a/cabal-install/src/Distribution/Client/ProjectBuilding.hs
+++ b/cabal-install/src/Distribution/Client/ProjectBuilding.hs
@@ -1,10 +1,10 @@
 {-# LANGUAGE BangPatterns #-}
 {-# LANGUAGE ConstraintKinds #-}
 {-# LANGUAGE DataKinds #-}
+{-# LANGUAGE FlexibleContexts #-}
 {-# LANGUAGE NamedFieldPuns #-}
 {-# LANGUAGE RecordWildCards #-}
 {-# LANGUAGE ScopedTypeVariables #-}
-{-# LANGUAGE TypeFamilies #-}
 {-# LANGUAGE NoMonoLocalBinds #-}
 
 module Distribution.Client.ProjectBuilding
diff --git a/cabal-install/src/Distribution/Client/ProjectPlanOutput.hs b/cabal-install/src/Distribution/Client/ProjectPlanOutput.hs
index 9ab68f58e8a..2867cca7559 100644
--- a/cabal-install/src/Distribution/Client/ProjectPlanOutput.hs
+++ b/cabal-install/src/Distribution/Client/ProjectPlanOutput.hs
@@ -509,7 +509,7 @@ data PostBuildProjectStatus = PostBuildProjectStatus
   -- or data file generation failing.
   --
   -- This is a subset of 'packagesInvalidByChangedLibDeps'.
-  , packagesLibDepGraph :: Graph (Node UnitId ElaboratedPlanPackage)
+  , packagesLibDepGraph :: Graph UnitId (Node UnitId ElaboratedPlanPackage)
   -- ^ A subset of the plan graph, including only dependency-on-library
   -- edges. That is, dependencies /on/ libraries, not dependencies /of/
   -- libraries. This tells us all the libraries that packages link to.
@@ -629,7 +629,7 @@ postBuildProjectStatus
               )
 
       -- The plan graph but only counting dependency-on-library edges
-      packagesLibDepGraph :: Graph (Node UnitId ElaboratedPlanPackage)
+      packagesLibDepGraph :: Graph UnitId (Node UnitId ElaboratedPlanPackage)
       packagesLibDepGraph =
         Graph.fromDistinctList
           [ Graph.N pkg (installedUnitId pkg) libdeps
diff --git a/cabal-install/src/Distribution/Client/ProjectPlanning.hs b/cabal-install/src/Distribution/Client/ProjectPlanning.hs
index 685e46dfa77..c6e6f7793f6 100644
--- a/cabal-install/src/Distribution/Client/ProjectPlanning.hs
+++ b/cabal-install/src/Distribution/Client/ProjectPlanning.hs
@@ -1,10 +1,10 @@
 {-# LANGUAGE DataKinds #-}
 {-# LANGUAGE DeriveFunctor #-}
 {-# LANGUAGE LambdaCase #-}
+{-# LANGUAGE MultiParamTypeClasses #-}
 {-# LANGUAGE NamedFieldPuns #-}
 {-# LANGUAGE RankNTypes #-}
 {-# LANGUAGE RecordWildCards #-}
-{-# LANGUAGE TypeFamilies #-}
 
 -- |
 -- /Elaborated: worked out with great care and nicety of detail; executed with great minuteness: elaborate preparations; elaborate care./
@@ -3380,8 +3380,7 @@ instance Package PrunedPackage where
 instance HasUnitId PrunedPackage where
   installedUnitId = Graph.nodeKey
 
-instance Graph.IsNode PrunedPackage where
-  type Key PrunedPackage = UnitId
+instance Graph.IsNode UnitId PrunedPackage where
   nodeKey (PrunedPackage elab _) = Graph.nodeKey elab
   nodeNeighbors (PrunedPackage _ deps) = deps
 
@@ -3472,7 +3471,7 @@ pruneInstallPlanPass1 pkgs
     pruned_packages :: [ElaboratedPlanPackage]
     pruned_packages = map (mapConfiguredPackage fromPrunedPackage) (fromMaybe [] $ Graph.closure graph roots)
 
-    closed_graph :: Graph.Graph ElaboratedPlanPackage
+    closed_graph :: Graph.Graph UnitId ElaboratedPlanPackage
     closed_graph = Graph.fromDistinctList pruned_packages
 
     -- whether any package has repl targets enabled, and we need to use multi-repl.
@@ -3828,10 +3827,10 @@ pruneInstallPlanToDependencies pkgTargets installPlan =
     -- if the remaining graph is broken or not, ie any packages with dangling
     -- dependencies. If there are then we cannot prune the given targets.
     checkBrokenDeps
-      :: Graph.Graph ElaboratedPlanPackage
+      :: Graph.Graph UnitId ElaboratedPlanPackage
       -> Either
           CannotPruneDependencies
-          (Graph.Graph ElaboratedPlanPackage)
+          (Graph.Graph UnitId ElaboratedPlanPackage)
     checkBrokenDeps graph =
       case Graph.broken graph of
         [] -> Right graph
diff --git a/cabal-install/src/Distribution/Client/ProjectPlanning/SetupPolicy.hs b/cabal-install/src/Distribution/Client/ProjectPlanning/SetupPolicy.hs
index a510ea2bff6..6dbfcd865bc 100644
--- a/cabal-install/src/Distribution/Client/ProjectPlanning/SetupPolicy.hs
+++ b/cabal-install/src/Distribution/Client/ProjectPlanning/SetupPolicy.hs
@@ -1,4 +1,4 @@
-{-# LANGUAGE TypeFamilies #-}
+{-# LANGUAGE MultiParamTypeClasses #-}
 
 -- | Setup.hs script policy
 --
@@ -170,9 +170,7 @@ instance Package NonSetupLibDepSolverPlanPackage where
   packageId (NonSetupLibDepSolverPlanPackage spkg) =
     packageId spkg
 
-instance IsNode NonSetupLibDepSolverPlanPackage where
-  type Key NonSetupLibDepSolverPlanPackage = SolverId
-
+instance IsNode SolverId NonSetupLibDepSolverPlanPackage where
   nodeKey (NonSetupLibDepSolverPlanPackage spkg) =
     nodeKey spkg
 
@@ -190,7 +188,7 @@ instance IsNode NonSetupLibDepSolverPlanPackage where
 packageSetupScriptSpecVersion
   :: SetupScriptStyle
   -> PackageDescription
-  -> Graph.Graph NonSetupLibDepSolverPlanPackage
+  -> Graph.Graph SolverId NonSetupLibDepSolverPlanPackage
   -> ComponentDeps [SolverId]
   -> Version
 -- We're going to be using the internal Cabal library, so the spec version of
diff --git a/cabal-install/src/Distribution/Client/ProjectPlanning/Types.hs b/cabal-install/src/Distribution/Client/ProjectPlanning/Types.hs
index 6aa1065d20e..3af8dd9934c 100644
--- a/cabal-install/src/Distribution/Client/ProjectPlanning/Types.hs
+++ b/cabal-install/src/Distribution/Client/ProjectPlanning/Types.hs
@@ -2,8 +2,8 @@
 {-# LANGUAGE FlexibleContexts #-}
 {-# LANGUAGE FlexibleInstances #-}
 {-# LANGUAGE LambdaCase #-}
+{-# LANGUAGE MultiParamTypeClasses #-}
 {-# LANGUAGE NamedFieldPuns #-}
-{-# LANGUAGE TypeFamilies #-}
 
 -- | Types used while planning how to build everything in a project.
 --
@@ -493,8 +493,7 @@ instance HasConfiguredId ElaboratedConfiguredPackage where
 instance HasUnitId ElaboratedConfiguredPackage where
   installedUnitId = elabUnitId
 
-instance IsNode ElaboratedConfiguredPackage where
-  type Key ElaboratedConfiguredPackage = UnitId
+instance IsNode UnitId ElaboratedConfiguredPackage where
   nodeKey = elabUnitId
   nodeNeighbors = elabOrderDependencies
 
diff --git a/cabal-install/src/Distribution/Client/SolverInstallPlan.hs b/cabal-install/src/Distribution/Client/SolverInstallPlan.hs
index c0f1ff4dd2c..8f0dd18f835 100644
--- a/cabal-install/src/Distribution/Client/SolverInstallPlan.hs
+++ b/cabal-install/src/Distribution/Client/SolverInstallPlan.hs
@@ -1,9 +1,4 @@
 {-# LANGUAGE DeriveGeneric #-}
-{-# LANGUAGE TypeFamilies #-}
-
------------------------------------------------------------------------------
-
------------------------------------------------------------------------------
 
 -- |
 -- Module      :  Distribution.Client.SolverInstallPlan
@@ -86,7 +81,7 @@ import qualified Distribution.Compat.Graph as Graph
 
 type SolverPlanPackage = ResolverPackage UnresolvedPkgLoc
 
-type SolverPlanIndex = Graph SolverPlanPackage
+type SolverPlanIndex = Graph SolverId SolverPlanPackage
 
 data SolverInstallPlan = SolverInstallPlan
   { planIndex :: !SolverPlanIndex
@@ -301,7 +296,7 @@ nonSetupClosure
   -> SolverPlanIndex
 nonSetupClosure index pkgids0 = closure Graph.empty pkgids0
   where
-    closure :: Graph SolverPlanPackage -> [SolverId] -> SolverPlanIndex
+    closure :: Graph SolverId SolverPlanPackage -> [SolverId] -> SolverPlanIndex
     closure completed [] = completed
     closure completed (pkgid : pkgids) =
       case Graph.lookup pkgid index of
diff --git a/cabal-install/src/Distribution/Client/Types.hs b/cabal-install/src/Distribution/Client/Types.hs
index 841a4dbc9d2..4ff9d84daa4 100644
--- a/cabal-install/src/Distribution/Client/Types.hs
+++ b/cabal-install/src/Distribution/Client/Types.hs
@@ -1,9 +1,3 @@
-{-# LANGUAGE TypeFamilies #-}
-
------------------------------------------------------------------------------
-
------------------------------------------------------------------------------
-
 -- |
 -- Module      :  Distribution.Client.Types
 -- Copyright   :  (c) David Himmelstrup 2005
diff --git a/cabal-install/src/Distribution/Client/Types/ConfiguredPackage.hs b/cabal-install/src/Distribution/Client/Types/ConfiguredPackage.hs
index 0b7d62e7e77..f051ef22c94 100644
--- a/cabal-install/src/Distribution/Client/Types/ConfiguredPackage.hs
+++ b/cabal-install/src/Distribution/Client/Types/ConfiguredPackage.hs
@@ -1,5 +1,5 @@
 {-# LANGUAGE DeriveGeneric #-}
-{-# LANGUAGE TypeFamilies #-}
+{-# LANGUAGE MultiParamTypeClasses #-}
 
 module Distribution.Client.Types.ConfiguredPackage
   ( ConfiguredPackage (..)
@@ -58,8 +58,7 @@ instance HasConfiguredId (ConfiguredPackage loc) where
 instance PackageFixedDeps (ConfiguredPackage loc) where
   depends = fmap (map (newSimpleUnitId . confInstId)) . confPkgDeps
 
-instance IsNode (ConfiguredPackage loc) where
-  type Key (ConfiguredPackage loc) = UnitId
+instance IsNode UnitId (ConfiguredPackage loc) where
   nodeKey = newSimpleUnitId . confPkgId
 
   -- TODO: if we update ConfiguredPackage to support order-only
diff --git a/cabal-install/src/Distribution/Client/Types/ReadyPackage.hs b/cabal-install/src/Distribution/Client/Types/ReadyPackage.hs
index e04b5af79c8..256d898b198 100644
--- a/cabal-install/src/Distribution/Client/Types/ReadyPackage.hs
+++ b/cabal-install/src/Distribution/Client/Types/ReadyPackage.hs
@@ -1,6 +1,8 @@
 {-# LANGUAGE DeriveGeneric #-}
+{-# LANGUAGE FlexibleInstances #-}
 {-# LANGUAGE GeneralizedNewtypeDeriving #-}
-{-# LANGUAGE TypeFamilies #-}
+{-# LANGUAGE MultiParamTypeClasses #-}
+{-# LANGUAGE UndecidableInstances #-}
 
 module Distribution.Client.Types.ReadyPackage
   ( GenericReadyPackage (..)
@@ -33,8 +35,7 @@ newtype GenericReadyPackage srcpkg = ReadyPackage srcpkg -- see 'ConfiguredPacka
     )
 
 -- Can't newtype derive this
-instance IsNode srcpkg => IsNode (GenericReadyPackage srcpkg) where
-  type Key (GenericReadyPackage srcpkg) = Key srcpkg
+instance IsNode key srcpkg => IsNode key (GenericReadyPackage srcpkg) where
   nodeKey (ReadyPackage spkg) = nodeKey spkg
   nodeNeighbors (ReadyPackage spkg) = nodeNeighbors spkg
 
diff --git a/cabal-install/tests/UnitTests/Distribution/Client/InstallPlan.hs b/cabal-install/tests/UnitTests/Distribution/Client/InstallPlan.hs
index 9db7109fbc6..3a783d3145b 100644
--- a/cabal-install/tests/UnitTests/Distribution/Client/InstallPlan.hs
+++ b/cabal-install/tests/UnitTests/Distribution/Client/InstallPlan.hs
@@ -1,5 +1,6 @@
 {-# LANGUAGE ConstraintKinds #-}
-{-# LANGUAGE TypeFamilies #-}
+{-# LANGUAGE FlexibleContexts #-}
+{-# LANGUAGE MultiParamTypeClasses #-}
 {-# LANGUAGE NoMonoLocalBinds #-}
 
 module UnitTests.Distribution.Client.InstallPlan (tests) where
@@ -169,8 +170,7 @@ instance Show TestInstallPlan where
 data TestPkg = TestPkg PackageId UnitId [UnitId]
   deriving (Eq, Show)
 
-instance IsNode TestPkg where
-  type Key TestPkg = UnitId
+instance IsNode UnitId TestPkg where
   nodeKey (TestPkg _ ipkgid _) = ipkgid
   nodeNeighbors (TestPkg _ _ deps) = deps