mapM /= traverse?

[Simon Marlow]

On 12/05/2015 15:26, Edward Kmett wrote:
> On Tue, May 12, 2015 at 3:58 AM, Simon Marlow <marlowsd at gmail.com
> <mailto:marlowsd at gmail.com>> wrote:
>
>
>     Yes, I'm not really concerned that mapM is a method of Traversable
>     rather than just being an alias for traverse, but I'm wondering why
>     we define it in the list instance rather than using the default.
>
>
> We were pretty paranoid about introducing space or time regressions and
> didn't have a proof that we wouldn't introduce them by changing
> something there, so we left it alone.

Ok good, so it looks like the answer is "we could change it, but 
benchmark first".  I can do that.  Thanks!

Cheers,
Simon