Proposal: Add Eq instance for Control.Exception.ErrorCall

[Michael Snoyman]

On Tue, Nov 27, 2012 at 1:59 PM, Henning Thielemann <
lemming at henning-thielemann.de> wrote:

>
> On Tue, 27 Nov 2012, Michael Snoyman wrote:
>
>  +1 on the proposal. Even if I'm opposed to partial functions, I'm in
>> favor of making it easier to test them reliably.
>>
>
> How can you be sure that you get a certain error? Depending on the order
> of evaluation you might get different error messages if there are multiple
> possible ways to fail. I think automated testing against specific error
> messages will not work reliably.
>

Sure, in some cases that's true. The idea would be to structure the test
case in such a way that we no with certainty which way it will fail.
Simon's initial example will always fail in the same way.

Michael
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