relaxing instance declarations

[Max Bolingbroke]

You could probably get away with just using two "where" clauses:

instance Foo a where
    bar = ...
  where
    auxilliary = ...




On 28 April 2013 18:42, Edward Kmett <ekmett at gmail.com> wrote:

> Makes sense. I'm not sure what a good syntactic story would be for that
> feature though. Just writing down member names that aren't in the class
> seems to be too brittle and error prone, and new keywords seems uglier than
> the current situation.
>
> Sent from my iPad
>
> On Apr 28, 2013, at 1:24 PM, Doug McIlroy <doug at cs.dartmouth.edu> wrote:
>
> > 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 gmail.com> 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 cs.dartmouth.edu
> >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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