[Haskell-cafe] Deprecation of MonadCatchIO-transformers
ariep at xs4all.nl
Wed Nov 6 14:45:01 UTC 2013
As discussed before <http://email@example.com/msg104498.html>, the interface of the MonadCatchIO packages
is effectively deprecated by the removal of the 'block' and 'unblock' functions
in base-4.7. I would like to deprecate MonadCatchIO-transformers now.
As there are quite a few reverse dependencies, and as there is at least one
use case that apparently cannot be migrated easily <http://firstname.lastname@example.org/msg104501.html>, I will try to keep the
package functioning, for now.
In order to do this, I followed Edward Z. Yang's suggestion, and re-
implemented the IO instances of block and unblock, in terms of GHC primitives.
The instance now reads
> import qualified Control.Exception.Extensible as E
> import GHC.Base (maskAsyncExceptions#)
> import GHC.IO (unsafeUnmask,IO(IO))
> instance MonadCatchIO IO where
> catch = E.catch
> block = \ (IO io) -> IO $ maskAsyncExceptions# io
> unblock = unsafeUnmask
You can get a release candidate for a new version 0.3.1.0, by
darcs get http://patch-tag.com/r/AriePeterson/MonadCatchIO-transformers
I would be most grateful if someone could review and/or test this under GHC
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