Horizon Haskell Platform

horizon-haskell.net.

Horizon is a haskell package set targetting new builds of GHC.

Package Set Policy

This package set has the following policy.

• GHC will advance as often as possible
• Nonversioned locations (git, unversioned tarballs) are permitted to allow GHC to advance.
• The following packages must always build:
  • aeson
  • beam-postgres
  • composite-base
  • dhall
  • haskell-language-server
  • hedgehog
  • pandoc
  • persistent-postgresql
  • polysemy
  • servant
  • sydtest
  • tasty
  • wai-app-static
  • warp

Updating the Package Set

Generating the nix expressions for the package set is a two step process.

1. Edit the horizon.dhall file.
2. Generate the nix expressions with nix run develop/#horizon-gen-nix.

You can edit the horizon.dhall file in one of two ways: manually using a text editor, or programatically using horizon-shell.

Using horizon-shell.

To use horizon-shell.

nix run develop/#horizon-shell

This is a haskell interpreter with a few shortcut functions available. Running tryToUpgradeEverything will poll hackage for any potential updates and add them to the dhall file. This will only modify the dhall, not the nix expressions. You must remember to run nix run develop/#horizon-gen-nix afterwards.

To quickly add a new package to the dhall, use the addHackage function. For example addHackage "optics".

Tweaking & Hacking

If you need to do additional manual overrides to the nix code, such as addPkgconfigDepends, edit the configuration/common.nix overlay, which is applied over the generated derivations.

If you need to nullify libraries, use the configuration/hacking.nix overlay. Try to leave a note as to why this library has been nullified.

Feedback

To build all packages, run

nix run develop/#feedback -- build

Hoogle

To run a hoogle server containing the entire package set. Do

nix run .#run-hoogle