start work on distributive
fix laziness in DList
factor and distribute on Lens
introduce `SafeApp` trait which calls `unsafePerformIO` on a specified IO action
second part of refactoring of `typelevel`

* create a new `syntax` package similar to `scalaz.syntax`
* implicits which produce proofs or witnesses don't have to be imported any more
* remove undesired path-dependencies in some types
improve type inference in folds
Coroutines
add lens operation
Update doc/DeveloperGuide.md
Bijections, Lens rewrite, Rename, Zip/Cozip/Unzip type classes, collapsing at arbitrary level explained here http://osdir.com/ml/scala/2012-01/msg00284.html
Merge branch 'bijection' into scalaz-seven
infinite heterogeneous lists
example for another approach to index-based access of HLists
Bijections, Lens rewrite, Rename, Zip/Cozip/Unzip type classes, collapsing at arbitrary level explained here http://osdir.com/ml/scala/2012-01/msg00284.html
Merge branch 'bijection' into scalaz-seven
Bijections, Lens rewrite, Rename, Zip/Cozip/Unzip type classes, collapsing at arbitrary level explained here http://osdir.com/ml/scala/2012-01/msg00284.html
Merge branch 'bijection' into scalaz-seven
rename costate file
Zip instances and UnwriterT
some and many