Proposal: Add Eq instance for Control.Exception.ErrorCall

[Simon Hengel]

On Tue, Nov 27, 2012 at 01:57:11PM +0000, Simon Marlow wrote:
> On 27/11/12 10:59, Simon Hengel wrote:
> >Hi,
> >I propose to add an Eq instance for ErrorCall.  The main motivation is
> >to make it more convenient to construct predicates that select specific
> >exceptions.
> >
> >My current use case is testing for expected exceptions.  In Hspec[1] we
> >use predicates for that, e.g.:
> >
> >   evaluate (head []) `shouldThrow` (== ErrorCall "Prelude.head: empty list")
> >
> >But I think it can be useful in other situations and it is consistent
> >with the fact that other common exception types have an Eq instance
> >(e.g. ArithException, IOException, ExitCode).
> >
> >Discussion period: 3 Weeks
> 
> Already did it, a few weeks ago:
> 
> http://www.haskell.org/pipermail/cvs-libraries/2012-October/016043.html

Thanks :)