[Haskell-cafe] is this an arrow?

[Johannes Waldmann]

Dear Cafe, I have the following types:

type Computer a b =  ( a -> IO ( Maybe b ) )
type Transformer a b c d =  Computer a ( b, c -> d )

For example, a SAT solver:
minisat :: Computer CNF Assignment,

and when I use it to solve an application problem
via transformation to SAT, I need
t :: Transformer Problem SAT Assignment Solution

Now - what is the proper abstraction? Is this an arrow somehow?
And is there already a type and a library that would
contain useful combinators like some of these:

http://autolat.imn.htwk-leipzig.de/gitweb/?p=box;a=blob;f=src/exotic/Strategy.hs;h=238b5f55fabf356e0ce484d0f6b882a06d6e6cfc;hb=HEAD

Thanks - J.W.

-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 262 bytes
Desc: OpenPGP digital signature
URL: <http://www.haskell.org/pipermail/haskell-cafe/attachments/20120413/48677a8c/attachment.pgp>