Delaying 7.10?

[Johan Tibell]

I think delaying is OK, but we should probably say something like "we're
delaying for X and Y, but that doesn't mean that you can not sneak in Z*".

* Unless Z is the StrictData language pragma and your name is Johan. ;)

On Thu, Jan 29, 2015 at 9:58 AM, Simon Peyton Jones <simonpj at microsoft.com>
wrote:

>  Friends
>
> In a call with a bunch of type hackers, we were discussing
>
>                https://ghc.haskell.org/trac/ghc/ticket/9858
>
> This is a pretty serious bug.  It allows a malicious person to construct
> his own unsafeCoerce, and so completely subverts Safe Haskell.
>
> Actually there are two bugs (see comment:19).  The first is easily fixed.
> But the second is not.
>
> We explored various quick fixes, but the real solution is not far out of
> reach.  It amounts to this:
>
> ·        Every data type is automatically in Typeable.  No need to say
> “deriving(Typeable)” or “AutoDeriveTypeable” (which would become deprecated)
>
> ·        In implementation terms, the constraint solver treats Typeable
> specially, much as it already treats Coercible specially.
>
> It’s not a huge job.  It’d probably take a couple of days of
> implementation work, and some time for shaking out bugs and consequential
> changes.  The biggest thing might be simply working out implementation
> design choices.  (For example, there is a modest code-size cost to making
> everything Typeable, esp because that includes the data constructors of the
> type (which can be used in types, with DataKinds).  Does that matter?
> Should we provide a way to suppress it?  If so, we’d also need a way to
> express whether or not the Typable instance exists in the interface file.)
>
> But it is a substantial change that will touch a lot of lines of code.
> Moreover, someone has to do it, and Iavor (who heroically volunteered)
> happens to be travelling next week.
>
> So it’s really not the kind of thing we would usually do after RC2.
>
> But (a) it’s serious and, as it happens, (b) there is also the BBP Prelude
> debate going on.
>
> Hence the question: should we simply delay 7.10  by, say, a month?  After
> all, the timetable is up to us.  Doing so might give a bit more breathing
> space to the BBP debate, which might allow time for reflection and/or
> implementation of modest features to help the transition.  (I know that
> several are under discussion.)  Plus, anyone waiting for 7.10 can simply
> use RC2, which is pretty good.
>
> Would that be a relief to the BBP debate?  Or any other opinions.
>
> Simon
>
> PS: I know, I know: there is endless pressure to delay releases to get
> stuff in.  If we give in to that pressure, we never make a release.  But we
> should know when to break our own rules.  Perhaps this is such an occasion.
>
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