Hamish Mackenzie 4d27798d6d Use fixed output derivations for bootstrap plans (#286) ...

Currently when a dependency of cabal-install or plan-to-nix changes
the cabal new-configure and plan-to-nix have to be rebuilt in order
to recalculate the plan-nix for bootstrap packages alex, happy and
hscolour.  We have pinned the inputs such as hackage index-state
so that the plan generated should be the same.  Unfortunately it can
still result in a long wait.

Haskell.nix does cache the result via haskellNixRoots when built on
iohk's hydra server.  But if you use a different version of nixpkgs
it is unlikely to work.  If you have access to a CI that populates a
nix cache you can add haskellNixRoots to your CI build, but if not
you are kind of stuck.

One option to help with this would be to include the plan-to-nix output
in the haskell.nix git repository.  But intermediate files in git is
not nice.

Instead this PR adds just the hashes of the output to the derivations
that runs plan-to-nix.  Since the inputs are fixed or should have
no affect on the result (GCC version for instance), we should
be able to rely on them remaining constant.

2019-11-02 01:21:30 +13:00

..

commands.md

More documentation (#179)

2019-06-15 07:11:52 +02:00

library.md

Use fixed output derivations for bootstrap plans (#286)

2019-11-02 01:21:30 +13:00

modules-preamble.md

More documentation (#179)

2019-06-15 07:11:52 +02:00