haskell/containers — pull request #54 by hvr (2014-09-27 13:21:08+00:00)
Title: Use defensive `Data.Foldable` import

With this `import`-style containers will compile warning free
with existing GHC versions as well as GHC HEAD (in its current form)

This change is also needed because `Data.Foldable` is planned to export
`null` and `length` which will otherwise clash with `Data.Sequence`