docs/tutorials/hackage-stackage.md · haskell.nix

git.iko.soy/haskell.nix

haskell.nix/docs/tutorials/hackage-stackage.md

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1# Bumping Hackage and Stackage snapshots

3`haskell.nix` relies on some generated data providing information about packages in Hackage and Stackage snapshots.

4These are kept in [`hackage.nix`](https://github.com/input-output-hk/hackage.nix) and [`stackage.nix`](https://github.com/input-output-hk/stackage.nix) respectively.

5If your project depends on a Hackage package, then the `hackage.nix` revision used must be new enough to contain that, and likewise for Stackage snaphots and `stackage.nix`.

7## Updating and pinning `hackage.nix` and `stackage.nix`

9`haskell.nix` pins particular revisions of these repositories internally, both for our own usage in testing, and so that users have a sensible default when getting started.

10These revisions are updated nightly, so you can get newer revisions of `hackage.nix` and `stackage.nix` by updating your revision of `haskell.nix` itself.

12However, this exposes you to changes in `haskell.nix` which you may not want, such as changes that force compiler rebuilds, or the occasional bug.

13Instead, you can pin `hackage.nix` and `stackage.nix` independently. For example:

15```nix

16let

17 # You can use a tool like `niv` to manage this boilerplate

18 hackageSrc = builtins.fetchTarball https://github.com/input-output-hk/hackage.nix/archive/master.tar.gz;

19 stackageSrc = builtins.fetchTarball https://github.com/input-output-hk/stackage.nix/archive/master.tar.gz;

20 haskellSrc = builtins.fetchTarball https://github.com/input-output-hk/haskell.nix/archive/master.tar.gz;

22 haskellNix = import haskellSrc {

23 # This allows you to override the pins used by `haskell.nix` internally

24 sourcesOverride = {

25 hackage = hackageSrc;

26 stackage = stackageSrc;

27 };

28 };

29in ...

30```

32This way you can change the revisions of `hackage.nix` and `stackage.nix`

33without changing `haskell.nix`.

35However, bear in mind that Stackage refers to Hackage, so your Stackage pin

36should never be newer than your Hackage pin.