Ability to sort large files

[dim]

I was looking to add a CLI extension to our very own lib https://github.com/bsm/extsort, until I stumbled across omegasort. It seems to support pretty much everything we need except that it is limited to memory and cannot operate on arbitrarily large files/streams.

Would you consider integrating extsort instead of reading all lines into memory? It should be a relatively trivial addition.

[autarch]

Would you consider integrating extsort instead of reading all lines into memory?

Yes, definitely. I'd actually thought on on-disk sorting as a possible option before, but I'd never looked into it.

I think it'd be best to just make this an additional CLI option for now. Is this something you'd be interesting in making a PR for?

[autarch]

This was a comment from back when omegasort was implemented in Go. This is no longer relevant.

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I'm taking a look at extsort and I see one impedance that might make integrating it challenging. My code uses sort functions with the signature func(i, j int) bool. The i and j arguments are slice indexes into the data being sorted. Internally, all of the functions are operating on a []string slice.

I think the right approach would be to make the omegasort sorters work like extsort, since they're all in an internal package with no public API.