GHC redundant constraint

gistfile1.txt

newtype Sym = Sym { unSym :: ByteString }
  deriving ( Eq, Generic, Hashable, Ord, IsString, MonoFoldable, Monoid, Semigroup, C.FromField, C.ToField )
type instance Element Sym = Word8


GHC 8.8 Warning:
================
    • Redundant constraint: Eq (Element Sym)
    • In an expression type signature:
           Eq (Element Sym) => Element Sym -> Sym -> Bool
      In the expression:
          ghc-prim-0.5.3:GHC.Prim.coerce
            @(Element ByteString -> ByteString -> Bool)
            @(Element Sym -> Sym -> Bool)
            (onotElem @ByteString) ::
            Eq (Element Sym) => Element Sym -> Sym -> Bool
      In an equation for ‘onotElem’:
          onotElem
            = ghc-prim-0.5.3:GHC.Prim.coerce
                @(Element ByteString -> ByteString -> Bool)
                @(Element Sym -> Sym -> Bool)
                (onotElem @ByteString) ::
                Eq (Element Sym) => Element Sym -> Sym -> Bool
      When typechecking the code for ‘onotElem’
        in a derived instance for ‘MonoFoldable Sym’:
        To see the code I am typechecking, use -ddump-deriv
    |
150 |   deriving ( Eq, Generic, Hashable, Ord, IsString, MonoFoldable, Monoid, Semigroup, C.FromField, C.ToField )
    |                                                    ^^^^^^^^^^^^