[Haskell-cafe] A Generic Ordering over Types

[Michael Sloan]

I'm not sure why cmptype lists the tuple instances explicitly, since the
plugin also handles tuple types.  I can delete those cases and it still
passes the tests.

-Michael

On Sun, Dec 29, 2019 at 12:51 AM Justin Paston-Cooper <
paston.cooper at gmail.com> wrote:

> Looks like cmptype wins on genericity. Out of interest, is there any
> alternative these days to writing the tuple instances of CmpType
> explicitly?
>
> On Sat, 28 Dec 2019 at 23:29, Michael Sloan <mgsloan at gmail.com> wrote:
> >
> > Cool approach!
> >
> > cmptype does something similar, but requires a ghc plugin:
> https://github.com/isovector/type-sets/tree/master/cmptype
> >
> > I suppose one advantage of cmptype is that it can work with types that
> cannot derive Generic, such as GADTs.
> >
> > -Michael
> >
> > On Sat, Dec 28, 2019 at 3:23 AM Justin Paston-Cooper <
> paston.cooper at gmail.com> wrote:
> >>
> >> Hello,
> >>
> >> I've defined a module which defines a Data.Type.Ordering over types
> >> which are instances of Generic:
> >>
> https://github.com/jpcooper/generic-type-ordering/blob/master/src/Data/Type/Ordering.hs
> .
> >> I was considering submitting it to Hackage if anyone finds this
> >> useful.
> >>
> >> I am using it in conjunction with Data.Type.Set (type-level-sets),
> >> which requires an ordering over the used types.
> >>
> >> The ordering works by first comparing the package, then the module,
> >> then the type name. I take it that the ordering as defined is correct
> >> over all types which are an instance of Generic.
> >>
> >> I wanted to check first whether this is done anywhere else, or in a
> >> different, better way. Can anyone advise?
> >>
> >> Cheers,
> >>
> >> Justin
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