Language Change Management (was: [Haskell-cafe] Monad of no `return` Proposal (MRP): Moving `return` out of `Monad`)

[wren romano]

On Mon, Oct 5, 2015 at 5:23 PM, Adam Foltzer <acfoltzer at gmail.com> wrote:
>>  Also I'm not sure if there would be less complaints if
>> AMP/FTP/MFP/MRP/etc as part of a new Haskell Report would be switched on all
>> at once in e.g. `base-5.0`, breaking almost *every* single package out there
>> at once.
>
> I doubt the number of complaints-per-change would be fewer, but I'm strongly
> in favor of moving away from what feels like a treadmill that doesn't value
> the time of developers and that doesn't account for the
> more-than-sum-of-parts cost of the "constant flux".

Broadly speaking, I'm a "fix it now rather than later" sort of person
in Haskell because I've seen how long things can linger before finally
getting fixed (even when everyone agrees on what the fix should be and
agrees that it should be done). However, as I mentioned in the
originating thread, I think that —at this point— when it comes to
AMP/FTP/MFP/MRP/etc we should really aim for the haskell' committee to
work out a comprehensive solution (as soon as possible), and then
enact all the changes at once when switching to
Haskell201X/base-5.0/whatevs. I understand the motivations for wanting
things to be field-tested before making it into the report, but I
don't think having a series of rapid incremental changes is the
correct approach here. Because we're dealing with the Prelude and the
core classes, the amount of breakage (and CPP used to paper over it)
here is much higher than our usual treadmill of changes; so we should
take that into account when planning how to roll the changes out.

-- 
Live well,
~wren