[Haskell-cafe] ANNOUNCE: category-extras 0.44.2

Edward Kmett ekmett at gmail.com
Tue May 6 10:34:12 EDT 2008

Dan Doel asked me to roll category-extras into my nascent comonad
transformer library, and the result is category-extras 0.44.2!

So since Dan's release a couple of weeks ago (
http://www.haskell.org/pipermail/haskell-cafe/2008-April/042240.html) we
have added:

 * Comonad Transformers. Context/ContextT, Reader/ReaderT.
* A suite of Bifunctors and combinators in Control.Bifunctor.* -- we attach
most of the logic usually associated with a monoidal/comonoidal category to
the individual Bifunctor since Hask is a rich category to begin with.
* A suite of Functors and combinators in Control.Functor.*
 * Pointed and copointed functors.
* Control.Recursion has been broken out into a Control.Morphism.* and
recoded to use a simpler distributive law.
* Type Indexed versions of Applicatives, Monads, and Comonads (including
Diatchki's Indexed State and Wadler's Delimited Continuation Parameterized
* Parameterized Monads a la Ghani and Johann's paper ICFP 07 paper, and
their Applicative and comonadic dual.
 * Higher-order hylo-, cata- and ana- morphisms.
* Higher-order Monads a la Ghani and Johann and their comonadic equivalents.
 * Kan extensions.
* BiKleisli arrows as seen in Uustalu and Vene's Signals and Comonads and
SIGFPE's recent posts
* The Pointer comonad
* Grabbed Iavor Diatchki's value-supply and rolled it in as
Control.Comonad.Supply to make it clearer that it is a comonad, and pave the
way towards a Supply comonad transformer
* A richer set of compositions to allow for construction of comonads and
monads not only from adjunctions, but also from pre-composition or
post-composition of a monad with a pointed functor, and similarly
pre-composition and post-composition of a comonad with a copointed functor.
* Generic functor zapping, zipping, unzipping, and cozipping as mentioned
recently on http://comonad.com/reader

There is still a lot to do in terms of adding back a lot of the
documentation from the original, documenting the extensions and fleshing out
all of the definable instances as the concepts have grown exceptionally

I definitely welcome feedback and additions.

In particular if you were using a feature that was supported by the old
library or is unnatural to program in the current one, let me know.

My goal is to gather a lot of this esoterica into one place and integrate it
into something cohesive.

darcs http://comonad.com/haskell/category-extras/


-Edward Kmett
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://www.haskell.org/pipermail/haskell-cafe/attachments/20080506/22408887/attachment-0001.htm

More information about the Haskell-Cafe mailing list