Data.Fixed Missing E4, E5, etc

[Andrew Martin]

Thanks for your response. I'm actually already doing you recommended in my
library. It does work, but I still think it would be better to have this in
base.

-Andrew Martin

On Wed, Aug 3, 2016 at 11:46 AM, Merijn Verstraaten <merijn at inconsistent.nl>
wrote:

> Hi Andrew,
>
> Data.Fixed actually already provides all the tools you need to support any
> arbitrary precision. As such, I don't see the need to add obscure
> precisions to the library in addition to the existing common ones. Using
> Data.Fixed with a 4 digit precision like you want can be achieved in 3
> lines of code in you geolite library. Simply define:
>
> data MyPrecision
> instance HasResolution MyPrecision where
>     resolution _ = 4
>
> and use "Fixed MyPrecision" as type in your library. As you can see in the
> haddocks, the Num, Real, RealFrac, etc. instances work for any arbitrary
> instance of HasResolution.
>
> Cheers,
> Merijn
>
> > On 3 Aug 2016, at 13:57, Andrew Martin <andrew.thaddeus at gmail.com>
> wrote:
> >
> > I've been working on a library for parsing geolite's GeoIP csv file
> > (
> http://hackage.haskell.org/package/geolite-csv-0.2/docs/Geolite-Types.html
> ).
> > In this file, the latitude and longitude are always given to four
> > decimal points of precision. It seems like the Fixed data type (from
> > Data.Fixed in base) is the best choice for representing this.
> >
> > However, the precision levels provided are:
> >
> > - E0
> > - E1
> > - E2
> > - E3
> > - E6
> > - E9
> > - E12
> >
> > I would like to propose adding all of the missing ones into Data.Fixed
> > as well. Even though needed a four-decimal-point-precision number is
> > uncommon, it's not unheard of. Admittedly, the precision offered by E11
> > seems unlikely to ever be needed, but I think it would be nice for
> > completeness. I would be happy to PR this if others agree that it's a
> > good idea.
> >
> > -Andrew Martin
> >
> > _______________________________________________
> > Libraries mailing list
> > Libraries at haskell.org
> > http://mail.haskell.org/cgi-bin/mailman/listinfo/libraries
>
>


-- 
-Andrew Thaddeus Martin
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mail.haskell.org/pipermail/libraries/attachments/20160803/c88fb7bb/attachment.html>