doc: add a generic section on exploring package sets (#317392)

this removes the hard-coded listing from the Haskell examples, which can later be replaced by
a dynamic one as for the Python interpreters

* fix broken reference

* clarify why using `nix-env --query` makes sense

Co-authored-by: wamirez <wamirez@protonmail.com>
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Valentin Gagarin 2024-06-28 12:10:56 +02:00 committed by GitHub
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2 changed files with 58 additions and 75 deletions

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@ -21,25 +21,14 @@ Many “normal” user facing packages written in Haskell, like `niv` or `cachix
are also exposed at the top level, and there is nothing Haskell specific to
installing and using them.
All of these packages are originally defined in the `haskellPackages` package
set and are re-exposed with a reduced dependency closure for convenience.
(see `justStaticExecutables` or `separateBinOutput` below)
All of these packages are originally defined in the `haskellPackages` package set.
The same packages are re-exposed with a reduced dependency closure for convenience (see `justStaticExecutables` or `separateBinOutput` below).
The `haskellPackages` set includes at least one version of every package from
Hackage as well as some manually injected packages. This amounts to a lot of
packages, so it is hidden from `nix-env -qa` by default for performance reasons.
You can still list all packages in the set like this:
:::{.note}
See [](#chap-language-support) for techniques to explore package sets.
:::
```console
$ nix-env -f '<nixpkgs>' -qaP -A haskellPackages
haskellPackages.a50 a50-0.5
haskellPackages.AAI AAI-0.2.0.1
haskellPackages.aasam aasam-0.2.0.0
haskellPackages.abacate abacate-0.0.0.0
haskellPackages.abc-puzzle abc-puzzle-0.2.1
```
Also, the `haskellPackages` set is included on [search.nixos.org].
The `haskellPackages` set includes at least one version of every package from [Hackage](https://hackage.haskell.org/) as well as some manually injected packages.
The attribute names in `haskellPackages` always correspond with their name on
Hackage. Since Hackage allows names that are not valid Nix without escaping,
@ -49,8 +38,7 @@ For packages that are part of [Stackage] (a curated set of known to be
compatible packages), we use the version prescribed by a Stackage snapshot
(usually the current LTS one) as the default version. For all other packages we
use the latest version from [Hackage](https://hackage.org) (the repository of
basically all open source Haskell packages). See [below](#haskell-available-
versions) for a few more details on this.
basically all open source Haskell packages). See [below](#haskell-available-versions) for a few more details on this.
Roughly half of the 16K packages contained in `haskellPackages` dont actually
build and are [marked as broken semi-automatically](https://github.com/NixOS/nixpkgs/blob/haskell-updates/pkgs/development/haskell-modules/configuration-hackage2nix/broken.yaml).
@ -63,68 +51,15 @@ How you can help with that is
described in [Fixing a broken package](#haskell-fixing-a-broken-package).
-->
`haskellPackages` is built with our default compiler, but we also provide other
releases of GHC and package sets built with them. You can list all available
compilers like this:
`haskellPackages` is built with our default compiler, but we also provide other releases of GHC and package sets built with them.
Available compilers are collected under `haskell.compiler`.
```console
$ nix-env -f '<nixpkgs>' -qaP -A haskell.compiler
haskell.compiler.ghc810 ghc-8.10.7
haskell.compiler.ghc90 ghc-9.0.2
haskell.compiler.ghc925 ghc-9.2.5
haskell.compiler.ghc926 ghc-9.2.6
haskell.compiler.ghc927 ghc-9.2.7
haskell.compiler.ghc92 ghc-9.2.8
haskell.compiler.ghc945 ghc-9.4.5
haskell.compiler.ghc946 ghc-9.4.6
haskell.compiler.ghc947 ghc-9.4.7
haskell.compiler.ghc94 ghc-9.4.8
haskell.compiler.ghc963 ghc-9.6.3
haskell.compiler.ghc96 ghc-9.6.4
haskell.compiler.ghc98 ghc-9.8.1
haskell.compiler.ghcHEAD ghc-9.9.20231121
haskell.compiler.ghc8107Binary ghc-binary-8.10.7
haskell.compiler.ghc865Binary ghc-binary-8.6.5
haskell.compiler.ghc924Binary ghc-binary-9.2.4
haskell.compiler.integer-simple.ghc8107 ghc-integer-simple-8.10.7
haskell.compiler.integer-simple.ghc810 ghc-integer-simple-8.10.7
haskell.compiler.native-bignum.ghc90 ghc-native-bignum-9.0.2
haskell.compiler.native-bignum.ghc902 ghc-native-bignum-9.0.2
haskell.compiler.native-bignum.ghc925 ghc-native-bignum-9.2.5
haskell.compiler.native-bignum.ghc926 ghc-native-bignum-9.2.6
haskell.compiler.native-bignum.ghc927 ghc-native-bignum-9.2.7
haskell.compiler.native-bignum.ghc92 ghc-native-bignum-9.2.8
haskell.compiler.native-bignum.ghc928 ghc-native-bignum-9.2.8
haskell.compiler.native-bignum.ghc945 ghc-native-bignum-9.4.5
haskell.compiler.native-bignum.ghc946 ghc-native-bignum-9.4.6
haskell.compiler.native-bignum.ghc947 ghc-native-bignum-9.4.7
haskell.compiler.native-bignum.ghc94 ghc-native-bignum-9.4.8
haskell.compiler.native-bignum.ghc948 ghc-native-bignum-9.4.8
haskell.compiler.native-bignum.ghc963 ghc-native-bignum-9.6.3
haskell.compiler.native-bignum.ghc96 ghc-native-bignum-9.6.4
haskell.compiler.native-bignum.ghc964 ghc-native-bignum-9.6.4
haskell.compiler.native-bignum.ghc98 ghc-native-bignum-9.8.1
haskell.compiler.native-bignum.ghc981 ghc-native-bignum-9.8.1
haskell.compiler.native-bignum.ghcHEAD ghc-native-bignum-9.9.20231121
haskell.compiler.ghcjs ghcjs-8.10.7
```
Each of those compiler versions has a corresponding attribute set built using
Each of those compiler versions has a corresponding attribute set `packages` built with
it. However, the non-standard package sets are not tested regularly and, as a
result, contain fewer working packages. The corresponding package set for GHC
9.4.5 is `haskell.packages.ghc945`. In fact `haskellPackages` is just an alias
for `haskell.packages.ghc964`:
```console
$ nix-env -f '<nixpkgs>' -qaP -A haskell.packages.ghc927
haskell.packages.ghc927.a50 a50-0.5
haskell.packages.ghc927.AAI AAI-0.2.0.1
haskell.packages.ghc927.aasam aasam-0.2.0.0
haskell.packages.ghc927.abacate abacate-0.0.0.0
haskell.packages.ghc927.abc-puzzle abc-puzzle-0.2.1
```
Every package set also re-exposes the GHC used to build its packages as `haskell.packages.*.ghc`.
### Available package versions {#haskell-available-versions}

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@ -2,6 +2,54 @@
The [standard build environment](#chap-stdenv) makes it easy to build typical Autotools-based packages with very little code. Any other kind of package can be accommodated by overriding the appropriate phases of `stdenv`. However, there are specialised functions in Nixpkgs to easily build packages for other programming languages, such as Perl or Haskell. These are described in this chapter.
Each supported language or software ecosystem has its own package set named `<language or ecosystem>Packages`, which can be explored in various ways:
- Search on [search.nixos.org](https://search.nixos.org/packages)
For example, search for [`haskellPackages`](https://search.nixos.org/packages?query=haskellPackages) or [`rubyPackages`](https://search.nixos.org/packages?query=rubyPackages).
- Navigate attribute sets with [`nix repl`](https://nixos.org/manual/nix/stable/command-ref/new-cli/nix3-repl).
This technique is generally useful to inspect Nix language data structures.
:::{.example #example-navigte-nix-repl}
# Navigate Java compiler variants in `javaPackages` with `nix repl`
```shell-session
$ nix repl '<nixpkgs>' -I nixpkgs=channel:nixpkgs-unstable
nix-repl> javaPackages.<tab>
javaPackages.compiler javaPackages.openjfx15 javaPackages.openjfx21 javaPackages.recurseForDerivations
javaPackages.jogl_2_4_0 javaPackages.openjfx17 javaPackages.openjfx22
javaPackages.mavenfod javaPackages.openjfx19 javaPackages.override
javaPackages.openjfx11 javaPackages.openjfx20 javaPackages.overrideDerivation
```
:::
- List all derivations on the command line with [`nix-env --query`](https://nixos.org/manual/nix/stable/command-ref/nix-env/query).
`nix-env` is the only convenient way to do that, as it will skip attributes that fail [assertions](https://nixos.org/manual/nix/stable/language/constructs#assertions), such as when a package is [marked as broken](#var-meta-broken), rather than failing the entire evaluation.
:::{.example #example-list-haskellPackages}
# List all Python packages in Nixpkgs
The following command lists all [derivations names](https://nixos.org/manual/nix/stable/language/derivations#attr-name) with their attribute path from the latest Nixpkgs rolling release (`nixpkgs-unstable`).
```shell-session
$ nix-env -qaP -f '<nixpkgs>' -A pythonPackages -I nixpkgs=channel:nixpkgs-unstable
```
```console
pythonPackages.avahi avahi-0.8
pythonPackages.boost boost-1.81.0
pythonPackages.caffe caffe-1.0
pythonPackages.caffeWithCuda caffe-1.0
pythonPackages.cbeams cbeams-1.0.3
```
:::
```{=include=} sections
agda.section.md
android.section.md