Biguint-literal crate

[newpavlov]

Drafted for RustCrypto/elliptic-curves#218.

[newpavlov]

I still need this branch and PR

[tarcieri]

Err whoops, not sure what happened here. Sorry about that.

[tarcieri]

@newpavlov I think crypto-bigint might accomplish the same sort of goal as what's in this PR, but using const fn instead of a proc macro. Here's an example:

https://github.com/RustCrypto/traits/pull/645/files#diff-369e56ff85c2cd28f4a387c6a341ae8c5880633480cb4f629b30f9c8a79523c5R45-R46

[newpavlov]

Yes, I've noticed that you've managed to implement const initialization and was pleasantly surprised that it is possible with the current version of const generics. I will close this PR after I migrate RustCrypto/elliptic-curves#218 to crypto-bigint. But I will have to start with learning more about how crypto-bigint is implemented, since I only have been able to take a cursory look at it before.

[tarcieri]

FYI, I'll probably look at adding some basic support for field elements to crypto-bigint, although unfortunately const generics aren't quite powerful enough yet to model them the way I'd really like (i.e. with the field modulus expressed as a const generic)

They'll probably not be ideal for things like elements of the base field, but they should be fine for representing scalar fields.