T12083a.hs:6:1: error: [GHC-91510]
    • Illegal qualified type: Num a => a
    • In the type synonym declaration for ‘Constrd’
    Suggested fix: Perhaps you intended to use RankNTypes

T12083a.hs:10:26: error:
    • Data constructor ‘ExistentiallyLost’ has existential type variables, a context, or a specialised result type
        ExistentiallyLost :: forall u. TC u => u -> ExistentiallyLost
        (Enable ExistentialQuantification or GADTs to allow this)
    • In the definition of data constructor ‘ExistentiallyLost’
      In the data type declaration for ‘ExistentiallyLost’