README.md

# Horizon Haskell Platform

[horizon-haskell.net](https://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
  * xmonad-contrib
  * xmonad
  * wai-app-static
  * warp
* Tags will be of the form `unstable-<yyyy>-<mm>-<dd>-r<N>` where any
  unversioned source is used.
* Tags will be of the form `stable-<yyyy>-<mm>-<dd>-r<N>` where all
stable sources are used.

## Updating the package set

The package set is generated from the `horizon.dhall` using the following command:

```
nix run 'git+https://gitlab.horizon-haskell.net/haskell/horizon-gen-nix?ref=refs/tags/0.9.0'
```

This will generate both the packages folder and the package set file. If you
want to regenerate a particular package in the packages folder, delete that file
from the packages folder. To regenerate the entire package set from scratch,
delete the packages folder.

If you need to do additional manual overrides to the nix code, such as
`addPkgconfigDepends`, edit the `configuration.nix` overlay, which is applied
afterwards.

## Programmmatic Updates

To use `horizon-shell`.

```
nix run 'git+https://gitlab.horizon-haskell.net/shells/horizon-shell?ref=refs/tags/0.0.3'
```

See the in-shell help for usage.