Yes indeed, Concurrent Clean actually just passes around the "world" object in "direct/explicit style" but uses uniquness typing to make sure nothing happens that would violate the nice FP paradigm (mainly referential transparency?). That is, I think it's like that :) -----Original Message----- From: haskell-cafe-bounces@haskell.org [mailto:haskell-cafe-bounces@haskell.org] On Behalf Of Brandon S. Allbery KF8NH Sent: Monday, October 15, 2007 3:49 PM To: jerzy.karczmarczuk@info.unicaen.fr Cc: haskell-cafe Cafe Subject: Re: [Haskell-cafe] do On Oct 15, 2007, at 7:02 , jerzy.karczmarczuk@info.unicaen.fr wrote:
IO is different, you *cannot* make it non-monadic.
Not really true; it's just much more painful. You just e.g. explicitly do what the ghc library's implementation of IO does: construct a chain of functions with an opaque (and optionally(?) existential to enforce the opacity) "RealWorld" type which is passed as state from one invocation to the next, with the "top level" application partially applied. Or one of the operationally equivalent tricks used by other Haskell runtime implementations, cf. "IO Inside". It's not so much hard as it is far too much "busywork" for a programmer to want to deal with when programming... hence hiding the scaffolding in the type, which is perhaps the most general description of what a Haskell monad actually is. -- brandon s. allbery [solaris,freebsd,perl,pugs,haskell] allbery@kf8nh.com system administrator [openafs,heimdal,too many hats] allbery@ece.cmu.edu electrical and computer engineering, carnegie mellon university KF8NH _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe