Generic order relations

[countvajhula]

See RRFI [Draft]: Equality and Order Relations Interface

This issue is splintered off from #16 to contain discussion on issues that pertain to generic order relations specifically (e.g. generic interfaces like the proposed gen:orderable, conventions for order-related APIs). The other one will continue to be used for equality-oriented discussion. The composite relations <= and >= and any attendant discussion around the relationship between order and equality could be carried on in either issue as the discussion warrants.

[slaymaker1907]

If we are doing changes to how hashing is done, I'd like to see the hash code method/function accept a hasher object. This would eliminate the need for providing a hash and a secondary hash function. I also think this style of hashing is easier to implement for individual objects.

Rust does this really well with std::hash::Hasher.

[slaymaker1907]

The other thing we should think about is how to handle order relations for inexact numbers. I assume Scheme/Racket already have ways to do this, but this could be a good time to consider how/if partial orders should be supported.

[AlexKnauth]

I've started a Partial Order design proposal here: #276

[soegaard]

It would be nice to have something similar to the chain operations in:
https://srfi.schemers.org/srfi-67/srfi-67.html