Hi Ian, thanks for responding to my plea! I am renaming this thread and moving it to libraries. Please respond there. I wrote:
http://haskell.org/haskellwiki/ListT_done_right and not the broken implementation that comes with mtl. (Finally fixed in 6.8? Please?)
Ian Lynagh wrote:
If you want to propose that mtl switches to a different definition of ListT then please see http://www.haskell.org/haskellwiki/Library_submissions
OK, then. This is a major rewrite of this module. So let me open up the topic for discussion even before posting a submission. Do we need to worry about breaking code? Not very much, I suspect. That "monad" really is broken - it's not a monad at all. The problem and its solution have been well known for years. I personally tried using the "standard" ListT for a while, just because it's the standard. Until I ran into enough problems that I finally slapped my forehead and said "forget it". But just in case: Is there anyone reading this who would be hurt by this change and opposes it? Should we provide a more gradual deprecation path (what is it)? Thanks, Yitz