+1 But I kind of wonder if there don't exists programs that will break due to this. Probably only those that people have actually put in some attention to cross-platform compatibility. Edward Excerpts from Ian Lynagh's message of Wed Oct 26 18:59:38 -0400 2011:
Hi all,
Haskell currently requires that multiple-reader single-writer locking is used on files. I understand the motivation for this was to try to protect people from running into problems due to lazy IO, but in practice I think it just causes more problems than it solves.
The decision may also have been influenced by the belief that this behaviour is enforced for all programs on Windows, but I am told that it is possible to get lock-free behaviour on Windows too.
I propose that we remove all the automatic locking from the libraries, and let the user do any locking that they wish to do themselves.
Attached are patches for ghc, base, process and unix. (not yet tested on Windows).
Suggested discussion period: Until 9 Nov 2011
Related GHC ticket: http://hackage.haskell.org/trac/ghc/ticket/4363
Thanks Ian