transformers 0.4: change in accessor function exports?

[Edward Kmett]

Carter,

You don't deprecate versions in hackage, you deprecate whole packages.

Slow down and let's let the man reply. ;)

-Edward


On Wed, May 7, 2014 at 8:32 AM, Carter Schonwald <carter.schonwald at gmail.com
> wrote:

> should the 0.4 release be temporarily marked deprecated so that breakages
> stop for a wee bit?
>
>
> On Tue, May 6, 2014 at 6:30 PM, Edward Kmett <ekmett at gmail.com> wrote:
>
>> That is the suggestion we are putting forth. =)
>>
>> -Edward
>>
>>
>> On Wed, May 7, 2014 at 7:54 AM, Merijn Verstraaten <
>> merijn at inconsistent.nl> wrote:
>>
>>> Wouldn't it be simpler/less breaking to keep "newtype Identity a =
>>> Identity { runIdentity :: a }" and simply hand write Show/Read instances
>>> that function asif it was "newtype Identity a = Identity a", giving us best
>>> of both worlds?
>>>
>>> Cheers,
>>> Merijn
>>>
>>>
>>> On May 6, 2014, at 23:30 , Edward Kmett wrote:
>>>
>>> It may make the code in transformers a bit more confusing for a handful
>>> of instances, but this is breaking almost every user I've talked to.
>>>
>>> This is proving to be a major breaking change as users commonly import
>>> StateT(..) and go off and use runStateT, etc.
>>>
>>> I wrote the imports in mtl 2.2 in such a way that if you recanted and
>>> chose to switch back to the old style, it'd still work.
>>>
>>> I just know that I personally have 200+ modules to change as a result,
>>> for no better experience as a user.
>>>
>>> -Edward
>>>
>>>
>>> On Wed, May 7, 2014 at 3:18 AM, Ross Paterson <R.Paterson at city.ac.uk>wrote:
>>>
>>>> On Tue, May 06, 2014 at 07:16:40PM +0300, Michael Snoyman wrote:
>>>> > One of the changes[1] in transformers 0.4 is as follows:
>>>> >
>>>> > 0.3:
>>>> >
>>>> >     newtype Identity a = Identity { runIdentity :: a }
>>>> >
>>>> > 0.4:
>>>> >
>>>> >     newtype Identity a = Identity a
>>>> >     runIdentity (Identity x) = x
>>>> >
>>>> > While this may seem benign, I've already seen three cases where this
>>>> caused
>>>> > breakage[2][3][4].
>>>> >
>>>> > Is there a reason for this change in 0.4? If not, I'd like to request
>>>> moving
>>>> > back to the previous formulation to avoid unnecessary breakage.
>>>>
>>>> Read and Show instances were introduced in 0.4.  With the record form,
>>>> the default instances for those classes would be very cumbersome.
>>>> The alternative of defining custom instances that differ from the
>>>> default
>>>> ones would make the interface more confusing.
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>>>
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>>
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