Proposal: derive Typeable for Data.Monoid types

João Cristóvão jmacristovao at
Tue May 27 07:12:01 UTC 2014


This was already discussed when I noticed the the Generic instances
were missing.

Edward suggested that: "The Generic and Generic1 instances clearly
belong with their definitions. They also deserve Typeable and Data."
(...) "FWIW- The committee is in favor of adding the Generic,
Generic1, Data and Typeable instances along with Num for Sum and

But I guess part of that was lost in the discussion, and did not end
up on the patch. My understanding was that it was supposed to.

There also seemed to be a consensus in raising a new issue (that I
then forgot to raise :( ) to do this for all newtypes in base...


2014-05-27 7:38 GMT+01:00 Michael Snoyman <michael at>:
> On Tue, May 27, 2014 at 9:31 AM, Roman Cheplyaka <roma at> wrote:
>> I was surprised to find out that wrappers like Last do not have Typeable
>> instances. Let's add them.
> +1
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