hackage-db: support cabal-install 3.10.1.0 XDG paths. #597
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athas
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Thanks! Can you also link to the upstream code that implements this in the comment for reference? This also shows that we should respect the |
From 3.10.1.0 onwards, cabal-install uses XDG directories to store its state and cache components. cabal2nix expects to find the Hackage tarball in ~/.cabal, where it may no longer be located. This commit changes cabal2nix to look in ~/.cabal if that directory exists (which matches the behaviour of cabal-install itself), but otherwise looks in the appropriate XDG directory.
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Link added. The Right Solution is perhaps to depend on |
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Seems like cabal-install has made our lives harder than it should be – namely you can also configure arbitrary location for the package db location. What's worse this is apparently rendered into the configuration file by default, so even if people move their config to xdg paths, it may still show up under Not quite sure yet how to proceed – we'll want to avoid depending on |
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The issue with paths being stored in the cabal config file is not new. It's been like that for a while - maybe forever. This PR does not make the situation worse. |
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True, but it'll be more likely to be a problem now. In any case that we'll have to prefer For anything else I'll implement |
Just like cabal-install, if CABAL_DIR is set, use that for all operations. The environment variable does of course not support any split between $XDG_CONFIG_HOME/cabal and $XDG_CACHE_HOME/cabal which seems like an oversight on upstream's part, but we don't need to care: we only ever care about the state dir, so users can just need to set that.
Since nixpkgs unstable now ships cabal-install 3.10.1.0 (23.05 will as well), we should get this feature released soon.
sternenseemann
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| -- resides at @"$HOME\/.cabal\/packages\/hackage.haskell.org\/00-index.tar"@. | ||
| -- Running the command @"cabal update"@ will keep that file up-to-date. | ||
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| -- resides in @$HOME\/.cabal\/packages\/hackage.haskell.org\/@. |
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Do we want to adapt this path to the new default?
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I don't think it's necessary.
| Nothing -> | ||
| if dotCabalExists | ||
| then pure dotCabal | ||
| else getXdgDirectory XdgCache "cabal" |
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| Nothing -> | |
| if dotCabalExists | |
| then pure dotCabal | |
| else getXdgDirectory XdgCache "cabal" | |
| Nothing | dotCabalExists -> pure dotCabal | |
| Nothing -> getXdgDirectory XdgCache "cabal" |
Really unimportant. Just suggesting it to learn whether you also like it better and if not, why not.
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This was copy-pasted from the cabal source code which doesn't seem to use guards much.
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I think having the control flow more explicit is more readable here (at least to me) and it also makes the diff easier to discern. If you'd want to make the code nice, you'd probably use Alternative or something, but can't be bothered, really :)
From 3.10.1.0 onwards, cabal-install uses XDG directories to store its state and cache components. cabal2nix expects to find the Hackage tarball in ~/.cabal, where it may no longer be located.
This commit changes cabal2nix to look in ~/.cabal if that directory exists (which matches the behaviour of cabal-install itself), but otherwise looks in the appropriate XDG directory.