Hi Robert, I looked over your proposal.
I'm not sure if I'm in favor of introducing a new keyword. It seems unnecessary. Also, note that my proposal differs in that thread local variables are not writable, but can only be changed by calling (e.g. in my API) 'withIOParam'. This is still just as general, because an IORef can be stored in a thread-local variable, but it makes it easier to reason about the more common use case where TLS is used to make IO a Reader; and it makes it easier to share modifiable state across more than one thread. I.e. if modifiable state is stored as 'IOParam (IORef a)' then the default is for the stored 'IORef a' to be shared across all threads; it can only be changed "locally" for a specified action and any sub-threads using 'withIOParam'; and if some library I use decides to fork a thread behind the scenes, it won't change my program's behavior. I think it is a good idea to have stdin, cwd, etc. be thread-local. I don't understand why the 'TL' monad is necessary, but I haven't read the proposal very carefully. Best, Frederik On Sat, Aug 05, 2006 at 02:18:58PM -0400, Robert Dockins wrote: > Sorry to jump into this thread so late. However, I'd like to take a moment > to remind everyone that some time ago I put a concrete proposal for > thread-local variables on the table. > > http://article.gmane.org/gmane.comp.lang.haskell.cafe/11010 > > I believe this proposal addresses the initialization issues that Einar has > been discussing. In my proposal, thread-local variables always have some > defined value, and they obtain their values at well-defined points. > > The liked message also gives several use cases that I felt motivated the > proposal. > > -- > Rob Dockins > > Talk softly and drive a Sherman tank. > Laugh hard, it's a long way to the bank. > -- TMBG > _______________________________________________ > Haskell mailing list > Haskell@haskell.org > http://www.haskell.org/mailman/listinfo/haskell > -- http://ofb.net/~frederik/ _______________________________________________ Haskell mailing list Haskell@haskell.org http://www.haskell.org/mailman/listinfo/haskell
