nixpkgs/doc/languages-frameworks/idris.section.md
Silvan Mosberger eda8c36795
doc/idris: Fix install instructions
Because of nix-env weirdness, I introduced a mistake in the docs in
https://github.com/NixOS/nixpkgs/pull/50182, this fixes it.
2019-06-15 18:25:41 +02:00

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# Idris packages
## Installing Idris
The easiest way to get a working idris version is to install the `idris` attribute:
```
$ # On NixOS
$ nix-env -i nixos.idris
$ # On non-NixOS
$ nix-env -i nixpkgs.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:
```
$ # On NixOS
$ nix-env -iA nixos.myIdris
$ # On non-NixOS
$ nix-env -iA nixpkgs.myIdris
```
To see all available Idris packages:
```
$ # On NixOS
$ nix-env -qaPA nixos.idrisPackages
$ # On non-NixOS
$ nix-env -qaPA nixpkgs.idrisPackages
```
Similarly, entering a `nix-shell`:
```
$ nix-shell -p 'idrisPackages.with-packages (with idrisPackages; [ contrib pruviloj ])'
```
## Starting Idris with library support
To have access to these libraries in idris, call it with an argument `-p <library name>` for each library:
```
$ 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`:
```
$ idris --listlibs
00prelude-idx.ibc
pruviloj
base
contrib
prelude
00pruviloj-idx.ibc
00base-idx.ibc
00contrib-idx.ibc
```
## 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
{ build-idris-package
, fetchFromGitHub
, contrib
, lightyear
, lib
}:
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";
sha256 = "1g4pi0swmg214kndj85hj50ccmckni7piprsxfdzdfhg87s0avw7";
};
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
```
$ 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
```
$ nix-build -A yaml
```