constrain
    :: Environment
    -> R.Region
    -> L.Literal
    -> TypeAnnot
    -> IO AnnotConstr
constrain _ region literal tipe =
  return $ CEqual region tipe $ SinglePattern (toCtorString literal) []
constrain
    :: Environment
    -> R.Region
    -> L.Literal
    -> TypeAnnot
    -> IO AnnotConstr
constrain _ region literal tipe =
  return $ CEqual region tipe $ SinglePattern (toCtorString literal) []
constrain _ region literal tipe =
  return $ CEqual region tipe $ SinglePattern (toCtorString literal) []