The current intention is to go ahead with MonadFail.

It sounds like we'll need to delay the warnings themselves until around 8.4.

We can add them, but not turn them on by default in the short term. This has the knock-on effect of delaying the whole plan a release or two, but otherwise the plan is very actionable.

A lot of the opposition comes from fear that we 'might do anything at any time'. If we're up front about what is coming and give sufficient notice and the ability for folks to maintain a reasonably wide backwards compatibility window without needing to dip into CPP or suppress warnings them most of those fears go away.

-Edward

On Fri, Oct 16, 2015 at 12:09 PM, David Luposchainsky <dluposchainsky@googlemail.com> wrote:
On 13.10.2015 16:29, Simon Peyton Jones wrote:
> Also, David, did our conversation at HX help you get un-stuck?

Hi Simon,

yes, it was definitely a good pointer. On the other hand, I found the Haskell
Exchange to be quite a frustrating event with respect to current events: there
was a load of very loud, but in my opinion very wrong, categorical opposition to
breaking changes in general.
I spent quite a bit of time worrying about MonadFail in the past, but right now
I'd like to wait for a "tentative yes" from the CLC before I keep going, because
I'm really not sure the mob is going to make me throw away my patch. Granted, a
lot of the discussion is about MRP, but many of the points brought up there are
equally valid against the MFP.

David