
<interactive>:4:1: error: [GHC-23894]
    • Illegal generalised algebraic data declaration for ‘T’
    • In the data declaration for ‘T’
    Suggested fix: Perhaps you intended to use GADTs

<interactive>:4:16: [GHC-25709]
     Data constructor ‘C’ has existential type variables, a context, or a specialised result type
        C :: T Int
     In the definition of data constructor ‘C’
      In the data type declaration for ‘T’
    Suggested fixes:
       Perhaps you intended to use ExistentialQuantification
       Perhaps you intended to use GADTs

ghci057.hs:4:3: error: [GHC-25709]
    • Data constructor ‘C’ has existential type variables, a context, or a specialised result type
        C :: T Int
    • In the definition of data constructor ‘C’
      In the data type declaration for ‘T’
    Suggested fixes:
       Perhaps you intended to use ExistentialQuantification
       Perhaps you intended to use GADTs

ghci057.hs:4:3: error: [GHC-25709]
    • Data constructor ‘C’ has existential type variables, a context, or a specialised result type
        C :: T Int
    • In the definition of data constructor ‘C’
      In the data type declaration for ‘T’
    Suggested fixes:
       Perhaps you intended to use ExistentialQuantification
       Perhaps you intended to use GADTs