On Wed, Dec 28, 2016 at 3:21 PM, Olaf Klinke <olf@aatal-apotheke.de> wrote:

> Am 28.12.2016 um 19:40 schrieb Jan-Willem Maessen <jmaessen@alum.mit.edu>:
>
> A caution on this alternative: the first component of the tuple won't be strict enough and you'll leak space. I think the proposed solution is better. Note that you *don't* necessarily need the strictness annotation on healthTopics – this shifts around when the list append gets run but won't change space much.
>
> -Jan-Willem Maessen
Thanks for clarifying this, Jan-Willem. So there ought to be stricter versions of the newtype wrappers in Data.Monoid. Even then, the tuple is not strict. Will that also leak space?

Yes, the fact that the tuple is strict means that Sum's strictness doesn't matter (and Sum is a newtype, so strictness doesn't really come into play).

I just thought the (Sum Int,[String]) type was a neat example of instance deriving.

Indeed! And if I were hacking up a one-shot script I'd probably do it that way.

Cheers,
Olaf