Merge pull request #110491 from neosimsim/agda-doc-fix-install-command

agda: fix code snippet for installing Agda
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Domen Kožar 2021-04-27 17:40:36 +02:00 committed by GitHub
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@ -2,16 +2,19 @@
## How to use Agda
Agda can be installed from `agda`:
```ShellSession
$ nix-env -iA agda
```
Agda is available as the [agda](https://search.nixos.org/packages?channel=unstable&show=agda&from=0&size=30&sort=relevance&query=agda)
package.
To use Agda with libraries, the `agda.withPackages` function can be used. This function either takes:
The `agda` package installs an Agda-wrapper, which calls `agda` with `--library-file`
set to a generated library-file within the nix store, this means your library-file in
`$HOME/.agda/libraries` will be ignored. By default the agda package installs Agda
with no libraries, i.e. the generated library-file is empty. To use Agda with libraries,
the `agda.withPackages` function can be used. This function either takes:
* A list of packages,
* or a function which returns a list of packages when given the `agdaPackages` attribute set,
* or an attribute set containing a list of packages and a GHC derivation for compilation (see below).
* or an attribute set containing a function which returns a list of packages when given the `agdaPackages` attribute set and a GHC derivation for compilation (see below).
For example, suppose we wanted a version of Agda which has access to the standard library. This can be obtained with the expressions:
@ -27,9 +30,66 @@ agda.withPackages (p: [ p.standard-library ])
or can be called as in the [Compiling Agda](#compiling-agda) section.
If you want to use a library in your home directory (for instance if it is a development version) then typecheck it manually (using `agda.withPackages` if necessary) and then override the `src` attribute of the package to point to your local repository.
If you want to use a different version of a library (for instance a development version)
override the `src` attribute of the package to point to your local repository
Agda will not by default use these libraries. To tell Agda to use the library we have some options:
```nix
agda.withPackages (p: [
(p.standard-library.overrideAttrs (oldAttrs: {
version = "local version";
src = /path/to/local/repo/agda-stdlib;
}))
])
```
You can also reference a GitHub repository
```nix
agda.withPackages (p: [
(p.standard-library.overrideAttrs (oldAttrs: {
version = "1.5";
src = fetchFromGitHub {
repo = "agda-stdlib";
owner = "agda";
rev = "v1.5";
sha256 = "16fcb7ssj6kj687a042afaa2gq48rc8abihpm14k684ncihb2k4w";
};
}))
])
```
If you want to use a library not added to Nixpkgs, you can add a
dependency to a local library by calling `agdaPackages.mkDerivation`.
```nix
agda.withPackages (p: [
(p.mkDerivation {
pname = "your-agda-lib";
version = "1.0.0";
src = /path/to/your-agda-lib;
})
])
```
Again you can reference GitHub
```nix
agda.withPackages (p: [
(p.mkDerivation {
pname = "your-agda-lib";
version = "1.0.0";
src = fetchFromGitHub {
repo = "repo";
owner = "owner";
version = "...";
rev = "...";
sha256 = "...";
};
})
])
```
See [Building Agda Packages](#building-agda-packages) for more information on `mkDerivation`.
Agda will not by default use these libraries. To tell Agda to use a library we have some options:
* Call `agda` with the library flag:
```ShellSession
@ -46,7 +106,7 @@ depend: standard-library
More information can be found in the [official Agda documentation on library management](https://agda.readthedocs.io/en/v2.6.1/tools/package-system.html).
## Compiling Agda
Agda modules can be compiled with the `--compile` flag. A version of `ghc` with `ieee754` is made available to the Agda program via the `--with-compiler` flag.
Agda modules can be compiled using the GHC backend with the `--compile` flag. A version of `ghc` with `ieee754` is made available to the Agda program via the `--with-compiler` flag.
This can be overridden by a different version of `ghc` as follows:
```nix
@ -65,6 +125,21 @@ A derivation can then be written using `agdaPackages.mkDerivation`. This has sim
* `libraryName` should be the name that appears in the `*.agda-lib` file, defaulting to `pname`.
* `libraryFile` should be the file name of the `*.agda-lib` file, defaulting to `${libraryName}.agda-lib`.
Here is an example `default.nix`
```nix
{ nixpkgs ? <nixpkgs> }:
with (import nixpkgs {});
agdaPackages.mkDerivation {
version = "1.0";
pname = "my-agda-lib";
src = ./.;
buildInputs = [
agdaPackages.standard-library
];
}
```
### Building Agda packages
The default build phase for `agdaPackages.mkDerivation` simply runs `agda` on the `Everything.agda` file.
If something else is needed to build the package (e.g. `make`) then the `buildPhase` should be overridden.
@ -80,10 +155,16 @@ By default, Agda sources are files ending on `.agda`, or literate Agda files end
## 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:
```nix
{ mkDerivation, standard-library, fetchFromGitHub }:
```
and `mkDerivation` should be called instead of `agdaPackages.mkDerivation`. Here is an example skeleton derivation for iowa-stdlib:
Note that the derivation function is called with `mkDerivation` set to `agdaPackages.mkDerivation`, therefore you
could use a similar set as in your `default.nix` from [Writing Agda Packages](#writing-agda-packages) with
`agdaPackages.mkDerivation` replaced with `mkDerivation`.
Here is an example skeleton derivation for iowa-stdlib:
```nix
mkDerivation {