Proposal: keep Data.Map.foldWithKey

Gregory Collins greg at
Fri Jan 14 13:18:40 CET 2011

On Fri, Jan 14, 2011 at 12:56 PM, Johan Tibell <johan.tibell at> wrote:
> Could you please clarify why containers cannot process (i.e. bump
> major/minor version numbers) independently of GHC. GHC can pick a
> version by the time of each release, but in between releases it seems
> fine for the library to be out of sync. I have two version of
> containers installed without problem.

Not only that, but these additions and the deprecation are consistent with a
minor version bump as per the package versioning policy:


> A.B is known as the major version number, and C the minor version
> number. When a package is updated, the following rules govern how the version
> number must change relative to the previous version:
> 1. If any entity was removed, or the types of any entities or the definitions
> of datatypes or classes were changed, or instances were added or removed,
> then the new A.B must be greater than the previous A.B. Note that modifying
> imports or depending on a newer version of another package may cause extra
> instances to be exported and thus force a major version change.
> 2. Otherwise, if only new bindings, types, classes or modules (but see below)
> were added to the interface, then A.B may remain the same but the new C must
> be greater than the old C.
> 3. Otherwise, A.B.C may remain the same (other version components may
> change).

If you want to wait until 7.2, that's fine, but if I'm not mistaken
"foldWithKey" has already been deprecated in the GHC 7 release of
containers and so the horse has already left the barn.

Gregory Collins <greg at>

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