diff --git a/semantic-diff.cabal b/semantic-diff.cabal
index 01cf9617a..d7d5d5eeb 100644
--- a/semantic-diff.cabal
+++ b/semantic-diff.cabal
@@ -18,7 +18,6 @@ library
                      , Category
                      , Control.Comonad.Cofree
                      , Control.Monad.Free
-                     , Data.Adjoined
                      , Data.Copointed
                      , Data.Functor.Both
                      , Data.Option
diff --git a/src/Data/Adjoined.hs b/src/Data/Adjoined.hs
deleted file mode 100644
index 0148799f6..000000000
--- a/src/Data/Adjoined.hs
+++ /dev/null
@@ -1,44 +0,0 @@
-module Data.Adjoined where
-
-import Control.Monad
-import Data.Sequence
-
-newtype Adjoined a = Adjoined { unAdjoined :: Seq a }
-  deriving (Eq, Foldable, Functor, Show, Traversable)
-
--- | A partial semigroup consists of a set and a binary operation which is associative but not necessarily closed.
--- |
--- | This is one possible generalization of semigroups, alongside the better-known Magma, which has a binary operation which is closed but not necessarily associative.
-class PartialSemigroup a where
-  coalesce :: a -> a -> Maybe a
-
-instance Applicative Adjoined where
-  pure = return
-  (<*>) = ap
-
-instance Monad Adjoined where
-  return = Adjoined . return
-  Adjoined a >>= f = case viewl a of
-    EmptyL -> Adjoined empty
-    (a :< as) -> Adjoined $ unAdjoined (f a) >< unAdjoined (Adjoined as >>= f)
-
-instance PartialSemigroup a => Monoid (Adjoined a) where
-  mempty = Adjoined empty
-  mappend = mappendBy coalesce
-
-type Coalesce a = a -> a -> Maybe a
-
-mappendBy :: Coalesce a -> Adjoined a -> Adjoined a -> Adjoined a
-mappendBy coalesce (Adjoined a) (Adjoined b) = case (viewr a, viewl b) of
-  (_, EmptyL) -> Adjoined a
-  (EmptyR, _) -> Adjoined b
-  (as :> a', b' :< bs) -> Adjoined $ maybe (a >< b) ((as ><) . (<| bs)) (coalesce a' b')
-
-instance PartialSemigroup Bool where
-  coalesce True = Just
-  coalesce False = const Nothing
-
-instance Monoid a => PartialSemigroup (Maybe a) where
-  coalesce Nothing _ = Nothing
-  coalesce _ Nothing = Nothing
-  coalesce (Just a) (Just b) = Just (Just (a `mappend` b))