By default, Agda sources are files ending on `.agda`, or literate Agda files ending on `.lagda`, `.lagda.tex`, `.lagda.org`, `.lagda.md`, `.lagda.rst`. The list of recognised Agda source extensions can be extended by setting the `extraExtensions` config variable.
## Adding Agda packages to Nixpkgs {#adding-agda-packages-to-nixpkgs}
## Maintaining the Agda package set on Nixpkgs {#maintaining-the-agda-package-set-on-nixpkgs}
We are aiming at providing all common Agda libraries as packages on `nixpkgs`,
and keeping them up to date.
Contributions and maintenance help is always appreciated,
but the maintenance effort is typically low since the Agda ecosystem is quite small.
The `nixpkgs` Agda package set tries to take up a role similar to that of [Stackage](https://www.stackage.org/) in the Haskell world.
It is a curated set of libraries that:
1. Always work together.
2. Are as up-to-date as possible.
While the Haskell ecosystem is huge, and Stackage is highly automatised,
the Agda package set is small and can (still) be maintained by hand.
### Adding Agda packages to Nixpkgs {#adding-agda-packages-to-nixpkgs}
To add an Agda package to `nixpkgs`, the derivation should be written to `pkgs/development/libraries/agda/${library-name}/` and an entry should be added to `pkgs/top-level/agda-packages.nix`. Here it is called in a scope with access to all other Agda libraries, so the top line of the `default.nix` can look like:
@ -192,3 +208,49 @@ mkDerivation {
This library has a file called `.agda-lib`, and so we give an empty string to `libraryFile` as nothing precedes `.agda-lib` in the filename. This file contains `name: IAL-1.3`, and so we let `libraryName = "IAL-1.3"`. This library does not use an `Everything.agda` file and instead has a Makefile, so there is no need to set `everythingFile` and we set a custom `buildPhase`.
When writing an Agda package it is essential to make sure that no `.agda-lib` file gets added to the store as a single file (for example by using `writeText`). This causes Agda to think that the nix store is a Agda library and it will attempt to write to it whenever it typechecks something. See [https://github.com/agda/agda/issues/4613](https://github.com/agda/agda/issues/4613).
In the pull request adding this library,
you can test whether it builds correctly by writing in a comment:
```
@ofborg build agdaPackages.iowa-stdlib
```
### Maintaining Agda packages
As mentioned before, the aim is to have a compatible, and up-to-date package set.
These two conditions sometimes exclude each other:
For example, if we update `agdaPackages.standard-library` because there was an upstream release,
this will typically break many reverse dependencies,
i.e. downstream Agda libraries that depend on the standard library.
In `nixpkgs` we are typically among the first to notice this,
since we have build tests in place to check this.
In a pull request updating e.g. the standard library, you should write the following comment: