GHC 7.6.1 / System.IO.Error.try

John Lato jwlato at
Wed Sep 19 02:27:29 CEST 2012

> From: Brandon Allbery <allbery.b at>
> On Mon, Sep 17, 2012 at 2:41 PM, Oren Ben-Kiki <haskell-oren at>wrote:
>> It seems that System.IO.Error no longer exports "try" and that breaks a
>> lot of packages I am using. I am trying to move my code to GHC 7.6.1, and
>> this seems to be a common source of problems (there are other issues,
>> alas...). Is there an ETA to when libraries would be GHC-7.6.1-compatible?
> Most of that stuff should be in Control.Exception, fwiw.

System.IO.Error's try (and catch) is not the same as that of Control.Exception,
because it only catches IOError's.  catch is slightly more involved to
change because its type is specified as catching only IOError, whereas
Control.Exception.catch nearly always needs a manual annotation of the
exception type.

Replacing System.IO.Error.try with System.IO.Error.tryIOError should
work, and is compatible with ghc's back to 7.2.

John L

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