Proposal: GHC.Generics marked UNSAFE for SafeHaskell

[John Lato]

Well, no.  Presumably the example shouldn't compile at all.  That message
is more an indication that the demonstration is working as intended.

On Mon, Oct 7, 2013 at 12:31 AM, Carter Schonwald <
carter.schonwald at gmail.com> wrote:

> i assume https://github.com/JohnLato/safe-bugtest/blob/master/Main.hs#L13should say
>     putStrLn "Should print \"Pos (2)\""
>
> rather than -2?
>
>
> On Mon, Oct 7, 2013 at 1:23 AM, Carter Schonwald <
> carter.schonwald at gmail.com> wrote:
>
>> ooo, thats illuminating.
>>
>> thanks for cooking that up
>>
>>
>> On Mon, Oct 7, 2013 at 1:13 AM, John Lato <jwlato at gmail.com> wrote:
>>
>>> On Sun, Oct 6, 2013 at 10:14 PM, Ryan Newton <rrnewton at gmail.com> wrote:
>>>
>>>>
>>>> On Sun, Oct 6, 2013 at 6:28 PM, Ganesh Sittampalam <ganesh at earth.li>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.
>>>
>>> _______________________________________________
>>> ghc-devs mailing list
>>> ghc-devs at haskell.org
>>> http://www.haskell.org/mailman/listinfo/ghc-devs
>>>
>>>
>>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://www.haskell.org/pipermail/ghc-devs/attachments/20131007/2b7deaef/attachment.html>