@@ -124,8 +124,8 @@ class Subset s t where
124124instance Subset '[] '[] where
125125 subset xs = Empty
126126
127−instance Subset '[] (x ': t) where
128− subset xs = Empty
127+instance Subset s t => Subset s (x ': t) where
128+ subset (Ext _ xs) = subset xs
129129
130130instance Subset s t => Subset (x ': s) (x ': t) where
131131 subset (Ext x xs) = Ext x (subset xs)