diff --git a/src/Data/Prodder.hs b/src/Data/Prodder.hs
--- a/src/Data/Prodder.hs
+++ b/src/Data/Prodder.hs
@@ -330,17 +330,3 @@
 toList :: forall c xs a. FoldProd c xs => (forall x. c x => x -> a) -> Prod xs -> [a]
 toList f = foldProd @c (pure . f)
 {-# INLINE CONLIKE toList #-}
-
-class x `Contains` y where
-  uncontain :: x -> y
-
-instance {-# OVERLAPPABLE #-} x `HasIndexIn` xs => Prod xs `Contains` x where
-  uncontain = extract
-
-instance {-# OVERLAPPABLE #-} (KnownNat (Length xs'), Strengthen xs xs') => Prod xs `Contains` Prod xs' where
-  uncontain = strengthen
-
-newtype Nested a = Nested { unNest :: a }
-
-instance {-# OVERLAPPABLE #-} (x `Contains` y, x `HasIndexIn` xs) => Prod xs `Contains` Nested y where
-  uncontain = Nested . uncontain @x @y . uncontain @(Prod xs) @x
diff --git a/src/Data/Summer.hs b/src/Data/Summer.hs
--- a/src/Data/Summer.hs
+++ b/src/Data/Summer.hs
@@ -219,17 +219,18 @@
   (==) = error "(==) base case: impossible by construction"
   {-# INLINE CONLIKE (==) #-}
 
+class (Show x, Typeable x) => ShowTypeable x
+instance (Show x, Typeable x) => ShowTypeable x
+
 -- | Showing extensible sums.
-instance Show (Sum '[]) where
-  showsPrec n uv = error "show base case: impossible by construction"
-instance (Show x, Typeable x, Show (Sum xs)) => Show (Sum (x ': xs)) where
-  showsPrec d uv@(UnsafeInj tag' x)
-    | tag' == 0 = showParen (d > 10) $
-          showString "Inj @"
-        . showParen True (showsPrec (d + 1) (typeRep (Proxy @x)))
-        . showString " "
-        . showParen True (showsPrec @x (d + 1) (unsafeCoerce x))
-    | otherwise = showsPrec @(Sum xs) d (unsafeForgetFirst uv)
+instance ApplyFunction ShowTypeable xs => Show (Sum xs) where
+  showsPrec d v = showParen (d > 10) $
+      showString "Inj @"
+    . apply @ShowTypeable (\(x :: x) ->
+        showsPrec (d + 1) (typeRep (Proxy @x))
+      . showString " "
+      . showParen True (showsPrec (d + 1) x)
+    ) v
 
 -- | Transforming one sum into a sum which contains all of the same types
 class Weaken xs ys where
diff --git a/summer.cabal b/summer.cabal
--- a/summer.cabal
+++ b/summer.cabal
@@ -1,6 +1,6 @@
 cabal-version:       2.4
 name:                summer
-version:             0.3.7.0
+version:             0.3.7.1
 synopsis:            An implementation of extensible products and sums
 description:         An implementation of extensible products and sums.
 license:             MIT
diff --git a/test/Test.hs b/test/Test.hs
--- a/test/Test.hs
+++ b/test/Test.hs
@@ -167,10 +167,12 @@
     considerTest = do
       let x :: Sum '[Int, Bool] = Inj (10 :: Int)
           y :: Sum '[Int, Bool] = Inj True
-      requires
-        [ (consider @Int x == Right 10, "x at Int is not considered to be 10"),
-          (consider @Int y == Left (Inj True), "x is not considered to be Left (Inj True)"),
-          (consider @Bool y == Right True, "x at Bool is not considered to be Right True")
+          z :: Sum '[Int, Bool, Char] = Inj @Int 10
+      requires' "consider"
+        [ consider @Int x == Right 10
+        , consider @Int y == Left (Inj True)
+        , consider @Bool y == Right True
+        , consider @Bool z == Left (Inj @Int 10)
         ]
     inmapTest = do
       let x :: Sum '[Int, Bool] = Inj (10 :: Int)
@@ -197,7 +199,15 @@
       require (apply @Show show x == "False") "apply does not work 0"
     unorderedMatchTest = do
       let x :: Sum '[Int, Bool] = Inj False
-      require (unorderedMatch x not (\(x :: Int) -> x == 10)) "unordered match does not work 0"
+      requires' "unordered match"
+        [ unorderedMatch x not (\(x :: Int) -> x == 10)
+        , unorderedMatch x (\(x :: Int) -> x == 10) not
+        ]
     showTest = do
       let x :: Sum '[Int, Bool] = Inj False
-      require (show x == "Inj @Bool False") "show sum does not work 0"
+      let y :: Sum '[Int, Bool] = Inj @Int 1
+      requires' "show sum"
+        [ show x == "Inj @Bool False"
+        , show y == "Inj @Int 1"
+        ]
+