On Mon, Oct 7, 2013 at 1:33 PM, Ryan Newton
Again, my use-case (closed/safe Eq & Ord instances) is a few steps removed from this Generics business and I don't feel strongly about how it gets done. But having *SOME* way of doing it will be a massive boon to my lab's particular effort at maximizing the abilities of guaranteed-Safe deterministic parallelism in Haskell. Further, I think anyone else who tries to do something in SafeHaskell that depends on guaranteeing a closed/controlled set of instances (SafeEq, SafeOrd but also others) based on GHC.Generics will *also* find this change useful.
Hi, In containers we have Data instances "This instance preserves data abstraction at the cost of inefficiency". Generic is a more modern way to address the same problem. This Generic instance for Set is just a more convenient way to use Set.toList/Set.fromList http://lpaste.net/94028, which are -XSafe functions right? For your problem I suggest using template-haskell to write your "SafeEq" "SafeOrd" instances. It will let you access unexported constructors too, which means people using LVish can maintain their abstractions for everybody except LVish. My understanding is that the proposed changes to ghc/Generic would mean that all data used with LVish would have to expose it's implementation to everybody through the derived Generic instance. Regards, Adam