Proposal: Deprecate and remove Prelude.catch and System.IO.Error.{catch, try}

Simon Marlow marlowsd at
Wed Jan 5 11:38:49 CET 2011

On 04/01/2011 18:20, Ian Lynagh wrote:
> On Mon, Dec 27, 2010 at 12:36:33PM +0000, Ian Lynagh wrote:
>>      Deprecate and remove Prelude.catch and System.IO.Error.{catch,try}
>> Suggested deadline: 24 Jan 2011.
> Summary so far:
> Deprecating/removing Prelude.catch seems to have consensus so far, with
> several people in favour and only one opposed.
> A couple more people thought that System.IO.Error ought to export
> functions to handle the exceptions that it talks about.
> GHC actually can't currently deprecate one export of 'catch' but not the
> other. Because of this, and because of the possible confusion etc with
> having 2 'catch' functions, I suggest we add catchIO and tryIO to
> System.IO.Error too. This will also give the new report a catch function
> it can refer to without having to worry about existential
> quantification etc.

What about the Haskell 98 compatibility problem?  Do we say in GHC 7.2 
that the haskell98 package can no longer be used together with base?


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