Re: Proposal: GHC.Generics marked UNSAFE for SafeHaskell

On Sun, Oct 6, 2013 at 10:14 PM, Ryan Newton wrote:

On Sun, Oct 6, 2013 at 6:28 PM, Ganesh Sittampalam wrote:

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- Referential transparency: e.g. no unsafePerformIO

- Module boundary control: no abstraction violation like Template

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Haskell and GeneralizedNewtypeDeriving - Semantic consistency: importing a safe module can't change existing code, so no OverlappingInstances and the like

Is this change necessary to preserve the existing properties, or are you

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hoping to add a new one?

I'm not currently aware of ways to break these invariants *just* with GHC.Generics. Hmm, but I would like to know why it is marked trustworthy and not inferred-safe...

How about this demo repo? https://github.com/JohnLato/safe-bugtest I'm really not a safe haskell expert, but I believe this is a demonstration of using GHC.Generics to violate a module's abstraction boundaries with SafeHaskell enabled. If I'm incorrect, I would appreciate if somebody could explain my error. If, however, I'm correct, then I think that Ryan's proposal of marking GHC.Generics Unsafe is the best way to remedy the problem. A possible stumbling block may involve base and package-trust, but I'm not certain of the current status. John L.