Non-controversial rewrite RULES for time package

[Ivan Lazar Miljenovic]

On 25 September 2011 20:12, Liyang HU <haskell.org at liyang.hu> wrote:
> Hi,
>
> The time package is too slow. :(
>
> A prime example is diffUTCTime, which invokes utcTimeToPOSIXSeconds,
> which in turn calls realToFrac :: DiffTime -> NominalDiffTime. The
> former of these two types notionally accounts for leap seconds, while
> the latter does not. Both are newtypes around Data.Fixed.Pico.
>
> Since realToFrac is used in the library only when we know the
> difference is within one day, the two notions coincide, and there is
> no need to account for leap seconds. Indeed it currently (or rather,
> its implementation of "fromRational . toRational") behaves as such.
>
> I propose we include some rewrite RULES to eliminate the round-trip
> via Rational. For the attached benchmark, I get a ~4x improvement in
> speed.
>
> Discussion period: 2 weeks.

I thought we only made proposals here for packages which have the
maintainer set to libraries at haskell.org; since time is maintained by
Ashley Yakeley, wouldn't you be better off just proposing this to him
directly? (I've CC'd this to him to make sure he gets it).

-- 
Ivan Lazar Miljenovic
Ivan.Miljenovic at gmail.com
IvanMiljenovic.wordpress.com