Platform policy question: API compatability in minor releases

wren ng thornton wren at
Sun May 10 01:18:03 EDT 2009

Duncan Coutts wrote:
> So by arguing for new features in minor releases we're saying we should
> have a 4-6 week cycle. New library features every 6 weeks.

Thanks for putting some numbers on that. (and, yikes! I'm convinced. I 
was under the impression that there'd be fewer minor releases than that.)

> Now perhaps 12 months is too long (I think it is). Perhaps 6 months is
> too long even (though many other groups have settled on 6 months). But
> surely 6 weeks is far too short. That means essentially no
> synchronisation effect at all.
> If the majority opinion is that 6 months is too long to wait for new
> features, then how about 4 months, or even 3? Do people see the point
> I'm trying to make about the value of synchronisation?

I think that, given the rate of change in the Haskell world, 12 months 
is far too long. And I agree that a big part of the platform should be 
to provide synchronization, for which 6 weeks isn't enough.

In choosing between 3, 4, or 6 months (for 4, 3, and 2 times per year) I 
think there's a balance that needs to be struck for the platform to be 
useful to users. If updates are too few and too far between (as has 
historically been the case), then active  users will update the packages 
individually, thus defeating the point of the platform. On the other 
side of things, synchronicity.

Of those three options, I think 4 months is probably ideal. Quarterly 
releases still don't give much time for synchronization. For stable 
packages (like are currently included) development is slower in terms of 
API changes, so 6 months may suffice, but if younger packages are added 
then I don't think biannual releases will allow the HP to track 
development closely enough.

I still think that it would be good to try to have a three stage model 
for releases, instead of the two stage model that seems to be assumed. 
Adding new packages or destructive API changes strike me as being very 
different from compatible API changes (which are, in turn, separate from 
big fixes and bundling fixes). I'd like to see these two types of 
changes being distinguished in terms of the release schedule.

Live well,

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