Differences in pattern matching syntax?

David Menendez dave at zednenem.com
Fri Jan 16 12:04:42 EST 2009

On Fri, Jan 16, 2009 at 11:07 AM, Simon Peyton-Jones
<simonpj at microsoft.com> wrote:
> So, clearly not a bug in GHC; but it would be more felicitous if it gave you a warning about the instance declaration for Eq RuleType.  The difficulty is that it's not clear when to warn; it's ok to use default methods, but you must define *either* (==) *or* (/=).

Why is (/=) a member of Eq in the first place? Is there any code that
defines (/=) and uses the default for (==)?

Dave Menendez <dave at zednenem.com>

More information about the Glasgow-haskell-users mailing list