Make Eq and Ord foreign functions less JS-specific

[andyarvanitis]

While working on updating the C++ backend (now using dump-corefn), I found these foreign function implementations to be problematic. A typed backend (combined with type erasure) doesn't work with the assumptions these make. Note the removal of Data.Ord.Unsafe.unsafeCompare -- I don't think anyone else would need it(?), but if so, it can be put back.

[LiamGoodacre]

Thanks @andyarvanitis, this looks great.

I'm happy for unsafeCompare to die; it does make this a breaking change.
Did a quick search on GitHub but didn't find any proper usages.
I doubt it's very commonly used, and it's easy enough to fix.

[bb010g]

Is this blocked on anything?

[andyarvanitis]

@bb010g Not that I'm aware of. Maybe @LiamGoodacre knows?

[hdgarrood]

It’s mostly because a breaking change to Prelude has a big knock on effect on essentially the entire ecosystem, forcing more or less everyone to update their package manifest files. Therefore we tend to leave any breaking changes sitting in PRs for a while until we have a few we need to make, and do them all together to reduce the frequency of major version bumps.

Come to think of it I think we should keep unsafeCompare in for the time being but add a deprecation warning; that way we can get this merged sooner.

[andyarvanitis]

Sounds good; I'll add unsafeCompare back in, along with a deprecation warning for its use.

[hdgarrood]

Thanks!