containers 0.6.4.1

Bug fixes

• Replace value-forcing variants of compose with lazy variants.
  • This brings compose closer in line with functions like union and intersection which don't evaluate any map values. (Thanks, Simon Jakobi)

Additions

• Add reverseTopSort to Data.Graph (Thanks, James Parker)

• Expose traverseMaybeWithKey from Data.IntMap.{Lazy,Strict} (Thanks, Simon
  Jakobi)

Other changes

• Improvements to the testsuite: #663, #662 (Thanks, Bertram Felgenhauer)

• Fix build with stack test (Thanks, Simon Jakobi)