transformers 0.4: change in accessor function exports?

Michael Snoyman michael at
Tue May 6 16:16:40 UTC 2014

One of the changes[1] in transformers 0.4 is as follows:


    newtype Identity a = Identity { runIdentity :: a }


    newtype Identity a = Identity a
    runIdentity (Identity x) = x

While this may seem benign, I've already seen three cases where this caused

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.


-------------- next part --------------
An HTML attachment was scrubbed...
URL: <>

More information about the Libraries mailing list