On Sun, Oct 6, 2013 at 10:14 PM, Ryan Newton <[email protected]> wrote:
> > On Sun, Oct 6, 2013 at 6:28 PM, Ganesh Sittampalam <[email protected]>wrote: > >> - Referential transparency: e.g. no unsafePerformIO >> > - Module boundary control: no abstraction violation like Template >> 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 >> 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.
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