-- | Common descriptions for generic data type errors. module Generic.Data.Function.Error where import GHC.TypeLits ( ErrorMessage(Text) ) -- | Common type error string for when you attempt to use a generic instance -- at an empty data type (e.g. 'Data.Void.Void', 'GHC.Generics.V1'). type ENoEmpty = 'Text "Requested generic instance disallows empty data type" -- | Common type error string for when GHC is asked to derive a non-sum -- instance, but the data type in question turns out to be a sum data type. -- -- No need to add the data type name here, since GHC's context includes the -- surrounding instance declaration. type EUnexpectedSum = 'Text "Cannot derive non-sum generic instance for sum data type" -- | Common type error string for when GHC is asked to derive a sum instance, -- but the data type in question turns out to be a non-sum data type. -- -- No need to add the data type name here, since GHC's context includes the -- surrounding instance declaration. type EUnexpectedNonSum = 'Text "Refusing to derive sum generic instance for non-sum data type"