Proposal: GHC.Generics marked UNSAFE for SafeHaskell
rrnewton at gmail.com
Tue Oct 15 03:02:54 UTC 2013
Hey, that's an awesome formulation! Thanks Pedro.
Any idea how much work this would be to implement in GHC, if it did garner
On Tue, Oct 8, 2013 at 3:48 AM, José Pedro Magalhães <dreixel at gmail.com>wrote:
> On Mon, Oct 7, 2013 at 10:32 AM, Dag Odenhall <dag.odenhall at gmail.com>wrote:
>> Here‘s a thought: doesn’t Generic already have an unused phantom type
>> that's only there “just in case we need to add something in the future”?
> No, it doesn't.
> Just a thought: what if we had a type family
> type family Derives (t :: k1) (c :: k2) :: Bool
> which would automatically be instantiated by GHC appropriately? E.g., if
> the user had the following code:
> data MyData = MyData deriving (Eq, Generic)
> deriving instance Show MyData
> instance Ord MyData
> GHC would automatically instantiate:
> type instance Derives MyData Eq = True
> type instance Derives MyData Generic = True
> type instance Derives MyData Show = True
> type instance Derives MyData Ord = False
> Would this be something Ryan could use for detecting safe instances for
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