Allowing --from and --to as an alternative to --from or --to
is hard to do with optparse-applicative!
The obvious approach of (pfrom <|> pto <|> pfromandto) does not work
when pfromandto uses the same option names as pfrom and pto do.
It compiles but the generated parser does not work for all desired
combinations.
Instead, have to parse optionally from and optionally to. When neither
is provided, the parser succeeds, but it's a result that can't be
handled. So, have to giveup after option parsing. There does not seem to
be a way to make an optparse-applicative Parser give up internally
either.
Also, need seek' because I first tried making fto be a where binding,
but that resulted in a hang when git-annex move was run without --from
or --to. I think because startConcurrency was not expecting the stages
value to contain an exception and so ended up blocking.
Sponsored-by: Dartmouth College's DANDI project
git-annex allows managing large files with git, without storing the file
contents in git. It can sync, backup, and archive your data, offline
and online. Checksums and encryption keep your data safe and secure. Bring
the power and distributed nature of git to bear on your large files with
git-annex.
For documentation, see doc/ or <https://git-annex.branchable.com/>
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