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

[Johan Tibell]

On Sun, Jul 26, 2009 at 3:34 AM, Ian Lynagh <igloo at earth.li> wrote:

> Hi all,
>
> I've made a ticket and proposal page for making the labelled field
> syntax stricter, e.g. making this illegal:
>
>    data A = A {x :: Int}
>
>    y :: Maybe A
>    y = Just A {x = 5}
>
> and requiring this instead:
>
>    data A = A {x :: Int}
>
>    y :: Maybe A
>    y = Just (A {x = 5})
>
> http://hackage.haskell.org/trac/haskell-prime/ticket/132
>
> 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. So I
hereby suggest that we make a recompile of Hackage a requirement for any
breaking language changes. I understand that it might not be that easy to
recompile all of Hackage at the moment so we should try to come up with some
step-by-step instructions on how to do it. In the future it would be nice to
have a little script that does it and spits out some statistics.

Cheers,

Johan
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