nixpkgs-suyu/doc/languages-frameworks/idris.section.md
Anderson Torres e671d3bbbd Nix docs: remove with lib; from example code
Following [Best Practices](https://nix.dev/guides/best-practices#with-scopes),
`with` is a problematic language construction and should be avoided.

Usually it is employed like a "factorization": `[ X.A X.B X.C X.D ]` is written
`with X; [ A B C D ]`.

However, as shown in the link above, the syntatical rules of `with` are not so
intuitive, and this "distributive rule" is very selective, in the sense that
`with X; [ A B C D ]` is not equivalent to `[ X.A X.B X.C X.D ]`.

However, this factorization is still useful to "squeeze" some code, especially
in lists like `meta.maintainers`.

On the other hand, it becomes less justifiable in bigger scopes. This is
especially true in cases like `with lib;` in the top of expression and in sets
like `meta = with lib; { . . . }`.

That being said, this patch removes most of example code in the current
documentation.

The exceptions are, for now
- doc/functions/generators.section.md
- doc/languages-frameworks/coq.section.md

because, well, they are way more complicated, and I couldn't parse them
mentally - yet another reason why `with` should be avoided!
2024-03-06 11:40:09 -03:00

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3.6 KiB
Markdown

# Idris {#idris}
## Installing Idris {#installing-idris}
The easiest way to get a working idris version is to install the `idris` attribute:
```ShellSession
$ nix-env -f "<nixpkgs>" -iA idris
```
This however only provides the `prelude` and `base` libraries. To install idris with additional libraries, you can use the `idrisPackages.with-packages` function, e.g. in an overlay in `~/.config/nixpkgs/overlays/my-idris.nix`:
```nix
self: super: {
myIdris = with self.idrisPackages; with-packages [ contrib pruviloj ];
}
```
And then:
```ShellSession
$ # On NixOS
$ nix-env -iA nixos.myIdris
$ # On non-NixOS
$ nix-env -iA nixpkgs.myIdris
```
To see all available Idris packages:
```ShellSession
$ # On NixOS
$ nix-env -qaPA nixos.idrisPackages
$ # On non-NixOS
$ nix-env -qaPA nixpkgs.idrisPackages
```
Similarly, entering a `nix-shell`:
```ShellSession
$ nix-shell -p 'idrisPackages.with-packages (with idrisPackages; [ contrib pruviloj ])'
```
## Starting Idris with library support {#starting-idris-with-library-support}
To have access to these libraries in idris, call it with an argument `-p <library name>` for each library:
```ShellSession
$ nix-shell -p 'idrisPackages.with-packages (with idrisPackages; [ contrib pruviloj ])'
[nix-shell:~]$ idris -p contrib -p pruviloj
```
A listing of all available packages the Idris binary has access to is available via `--listlibs`:
```ShellSession
$ idris --listlibs
00prelude-idx.ibc
pruviloj
base
contrib
prelude
00pruviloj-idx.ibc
00base-idx.ibc
00contrib-idx.ibc
```
## Building an Idris project with Nix {#building-an-idris-project-with-nix}
As an example of how a Nix expression for an Idris package can be created, here is the one for `idrisPackages.yaml`:
```nix
{ lib
, build-idris-package
, fetchFromGitHub
, contrib
, lightyear
}:
build-idris-package {
name = "yaml";
version = "2018-01-25";
# This is the .ipkg file that should be built, defaults to the package name
# In this case it should build `Yaml.ipkg` instead of `yaml.ipkg`
# This is only necessary because the yaml packages ipkg file is
# different from its package name here.
ipkgName = "Yaml";
# Idris dependencies to provide for the build
idrisDeps = [ contrib lightyear ];
src = fetchFromGitHub {
owner = "Heather";
repo = "Idris.Yaml";
rev = "5afa51ffc839844862b8316faba3bafa15656db4";
hash = "sha256-h28F9EEPuvab6zrfeE+0k1XGQJGwINnsJEG8yjWIl7w=";
};
meta = {
description = "Idris YAML lib";
homepage = "https://github.com/Heather/Idris.Yaml";
license = lib.licenses.mit;
maintainers = [ lib.maintainers.brainrape ];
};
}
```
Assuming this file is saved as `yaml.nix`, it's buildable using
```ShellSession
$ nix-build -E '(import <nixpkgs> {}).idrisPackages.callPackage ./yaml.nix {}'
```
Or it's possible to use
```nix
with import <nixpkgs> {};
{
yaml = idrisPackages.callPackage ./yaml.nix {};
}
```
in another file (say `default.nix`) to be able to build it with
```ShellSession
$ nix-build -A yaml
```
## Passing options to `idris` commands {#passing-options-to-idris-commands}
The `build-idris-package` function provides also optional input values to set additional options for the used `idris` commands.
Specifically, you can set `idrisBuildOptions`, `idrisTestOptions`, `idrisInstallOptions` and `idrisDocOptions` to provide additional options to the `idris` command respectively when building, testing, installing and generating docs for your package.
For example you could set
```nix
build-idris-package {
idrisBuildOptions = [ "--log" "1" "--verbose" ]
...
}
```
to require verbose output during `idris` build phase.