When I implemented this stuff yesterday, I included `Deep` variants for each function which used NFData. I'm debating whether I think the right recommendation is to, by default, use the `async`/NFData versions of catch, handle, and try, or to have them as separate functions.
I wrote up the blog post, both on the Yesod blog[1] and School of Haskell[2]. The latter's a bit easier to use since it includes active code snippets. [1] http://www.yesodweb.com/blog/2013/07/catching-all-exceptions [2] https://www.fpcomplete.com/user/snoyberg/general-haskell/exceptions/catching-all-exceptions On Fri, Jul 12, 2013 at 4:03 AM, John Lato <jwl...@gmail.com> wrote: > I agree that how the exception was thrown is more interesting than the > type. I feel like there should be a way to express the necessary > information via the type system, but I'm not convinced it's easy (or even > possible). > > Another issue to be aware of is that exceptions can be thrown from pure > code, so if you don't fully evaluate your return value an exception can be > thrown later, outside the catch block. In practice this usually means an > NFData constraint, or some other constraint for which you can guarantee > evaluation. > > In the past I've been pretty vocal about my opposition to exceptions. > It's still my opinion that they do not make it easy to reason about > exceptional conditions. Regardless, as Haskell has them and uses them, I'd > like to see improvements if possible. So if anyone is exploring the design > space, I'd be willing to participate. > > > On Fri, Jul 12, 2013 at 12:57 AM, Michael Snoyman <mich...@snoyman.com>wrote: > >> >> >> >> On Thu, Jul 11, 2013 at 6:07 PM, Felipe Almeida Lessa < >> felipe.le...@gmail.com> wrote: >> >>> On Thu, Jul 11, 2013 at 10:56 AM, Michael Snoyman <mich...@snoyman.com> >>> wrote: >>> > The only >>> > approach that handles the situation correctly is John's separate thread >>> > approach (tryAll3). >>> >>> I think you meant "tryAll2" here. Got me confused for some time =). >>> >>> Cheers, >>> >>> -- >>> Felipe. >>> >> >> Doh, yes, I did, thanks for the clarification. >> >> After playing around with this a bit, I was able to get an implementation >> of try, catch, and handle which work for any non-async exception, in monad >> transformers which are instances of MonadBaseControl (from monad-control). >> I'll try to write up my thoughts in something more coherent, likely a blog >> post. >> >> Michael >> > >
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