transformers 0.4: change in accessor function exports?

[Henning Thielemann]

Am 07.05.2014 10:49, schrieb Joachim Breitner:
> Hi,
>
> Am Mittwoch, den 07.05.2014, 08:33 +0200 schrieb Henning Thielemann:
>> Am 07.05.2014 01:03, schrieb John Lato:
>>> I don't really care one way or the other how this is resolved, but does
>>> it strike anyone else that current practices must be remarkably fragile
>>> for such a minor change (which doesn't even change exported names!) to
>>> supposedly cause so much breakage?
>>
>> With qualified imports there would be no breakage ...
>>
>> However, names in mtl and thus transformers were not designed for
>> qualified import. :-(
>
> would it?
>
> /tmp $ echo 'module Foo where newtype Foo = Foo {unFoo :: ()}' > Foo.hs
> /tmp $ echo 'module Bar where import qualified Foo (Foo(..)) ; bar = Foo.unFoo' > Bar.hs

With qualified import I mean

import qualified Foo as Foo


Importing qualified with explicit import list is somehow done twice, 
because Foo.unFoo cannot clash with other identifiers, unless you use 
the abbreviation Foo twice.

> /tmp $ ghc -c Foo.hs; ghc -c Bar.hs
> /tmp $ echo 'module Foo where newtype Foo = Foo (); unFoo (Foo x) = x ' > Foo.hs
> /tmp $ ghc -c Foo.hs; ghc -c Bar.hs
>
> Bar.hs:1:57: Not in scope: `Foo.unFoo'