relaxing instance declarations

Doug McIlroy doug at
Sun Apr 28 19:24:58 CEST 2013

Not always. For example, you can't mess with the declaration
of a standard class, such as Num.

On Sun, Apr 28, 2013 at 12:06 PM, Edward Kmett <ekmett at> wrote:

> You can always put those helper functions in the class and then just not
> export them from the module.

On Sun, Apr 28, 2013 at 10:49 AM, Doug McIlroy <doug at>wrote:

> Is there any strong reason why the where clause in an instance
> declaration cannot declare anything other than class
> operators? If not, I suggest relaxing the restriction.
> It is not unusual for declarations of class operators to
> refer to special auxiliary functions. Under current rules
> such functions have to be declared outside the scope in
> which they are used.
> Doug McIlroy

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