Should exhaustiveness testing be on by default?

Lennart Augustsson lennart at
Sun May 17 21:18:19 EDT 2009

The exhaustiveness checker in ghc is not good.  It reports
non-exhaustive matching a bit too often and also the error messages
are often not in terms of the original source but some desugared

If those things were improved I think it should be always on.

On Mon, May 18, 2009 at 12:53 AM, Don Stewart <dons at> wrote:
> I'm not sure I'd want -Wall on by default (though being -Wall clean is
> very good). But exhaustive pattern checking might well help out a lot of
> people coming from untyped backgrounds.
> Ron's also wondering why exhaustive pattern checking isn't on ?
> Anyone know why it isn't the default?
> -- Don
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