64-bit integers are not enough

[erin-desu]

Is your feature request related to a problem?

I am trying to create IPv6 address registry where I have a common prefix I just register suffices. As IPv6 addresses are 128-bit long, I can't even create a mask larger than 64 bits.

Proposed solution

Introduce 128-bit integers or choose the Python-like solution and allow for arbitrary-sized ones.

Alternative solutions

Cope with workarounds like storing two 64-bit integers and suffer.

Additional context

None

Checklist

• [X] checked [latest Nix manual] ([source])
• [X] checked [open feature issues and pull requests] for possible duplicates

[roberth]

Nix has previously eliminated a similar yet very different such pain in the form of floating point number support. I believe that was a mistake for a reproducible language, but large integers principally don't have the kind of underspecification issues and are much more suitable for a language that boasts reproducibility (which necessitates portability and stability of its behavior over time).

In fact, native support for large numbers would be a very useful building block for building an alternative to floating point numbers

• https://github.com/NixOS/nix/issues/13997

Instead of 128 bits, I would prefer to go directly to integers of arbitrary size. We already have those in our closure anyway, e.g. openssl.

[xokdvium]

Triaged during today's meeting:

• @edolstra Seems like a "blob" (arbitrary binary data) type would be sufficient for IPv6 case without the complication of multiplication/division.
• @xokdvium Boost has lightweight arbitrary-precision libraries if that comes to it.
• @edolstra Native IPv6 type could possibly be an option.
  • @xokdvium Plugin could work as well.
• @roberth Fixing the nixpkgs library with available primitives without drastically increasing the complexity of the language sounds plausible.

Cope with workarounds like storing two 64-bit integers

@xokdvium This particular use-case doesn't have a particularly high overhead from lack of arbitrary-precision integers. Though other cases might not be so.