[Haskell-cafe] Recompiling Hackage to estimate the impact of a change [Was: StricterLabelledFieldSyntax]

[Ian Lynagh]

On Sun, Jul 26, 2009 at 08:21:00AM +0200, Johan Tibell wrote:
> On Sun, Jul 26, 2009 at 3:34 AM, Ian Lynagh <igloo at earth.li> wrote:
> 
> > http://hackage.haskell.org/trac/haskell-prime/wiki/StricterLabelledFieldSyntax
> >
> 
> In general, I think it would be a good idea to provide some statistics of
> how many packages would break as the result of a backwards incompatible
> change. Without that data I find it hard to do a cost-benefit analysis.

To some extent you are right, and if we had an easy to to get those
stats when I would be in favour of doing so.

But it is important to remember that a count of packages that break
won't tell you how hard it would be to fix them. For example, the
complete diff needed to fix old-time for StricterLabelledFieldSyntax
was:

-   toClockTime cal{ctMonth=month', ctYear=year'}
+   toClockTime $ cal{ctMonth=month', ctYear=year'}


Thanks
Ian