julia: add documentation to manual + release note

doc/languages-frameworks/index.md

@@ -24,6 +24,7 @@ idris.section.md
 ios.section.md
 java.section.md
 javascript.section.md
+julia.section.md
 lisp.section.md
 lua.section.md
 maven.section.md

doc/languages-frameworks/julia.section.md

@@ -0,0 +1,54 @@
+# Julia {#language-julia}
+
+## Introduction {#julia-introduction}
+
+Nixpkgs includes Julia as the `julia` derivation. You can get specific versions by looking at the other `julia*` top-level derivations available. For example, `julia_19` corresponds to Julia 1.9. We also provide the current stable version as `julia-stable`, and an LTS version as `julia-lts`.
+
+Occasionally, a Julia version has been too difficult to build from source in Nixpkgs and has been fetched prebuilt instead. These Julia versions are differentiated with the `*-bin` suffix; for example, `julia-stable-bin`.
+
+## julia.withPackages {#julia-withpackage}
+
+The basic Julia derivations only provide the built-in packages that come with the distribution.
+
+You can build Julia environments with additional packages using the `julia.withPackages` command. This function accepts a list of strings representing Julia package names. For example, you can build a Julia environment with the `Plots` package as follows.
+
+```nix
+julia.withPackages ["Plots"]
+```
+
+Arguments can be passed using `.override`. For example:
+
+```nix
+(julia.withPackages.override {
+  precompile = false; # Turn off precompilation
+}) ["Plots"]
+```
+
+Here's a nice way to run a Julia environment with a shell one-liner:
+
+```sh
+nix-shell -p 'julia.withPackages ["Plots"]' --run julia
+```
+
+### Arguments {#julia-withpackage-arguments}
+
+* `precompile`: Whether to run `Pkg.precompile()` on the generated environment.
+
+  This will make package imports faster, but may fail in some cases. For example, there is an upstream issue with `Gtk.jl` that prevents precompilation from working in the Nix build sandbox, because the precompiled code tries to access a display. Packages like this will work fine if you build with `precompile=false`, and then precompile as needed once your environment starts. Defaults to `true`.
+
+* `extraLibs`: Extra library dependencies that will be placed on the `LD_LIBRARY_PATH` for Julia.
+
+  Should not be needed as we try to obtain library dependencies automatically using Julia's artifacts system.
+
+* `makeWrapperArgs`: Extra arguments to pass to the `makeWrapper` call which we use to wrap the Julia binary.
+* `setDefaultDepot`: Whether to automatically prepend `$HOME/.julia` to the `JULIA_DEPOT_PATH`.
+
+  This is useful because Julia expects a writable depot path as the first entry, which the one we build in Nixpkgs is not. If there's no writable depot, then Julia will show a warning and be unable to save command history logs etc. Defaults to `true`.
+
+* `packageOverrides`: Allows you to override packages by name by passing an alternative source.
+
+  For example, you can use a custom version of the `LanguageServer` package by passing `packageOverrides = { "LanguageServer" = fetchFromGitHub {...}; }`.
+
+* `augmentedRegistry`: Allows you to change the registry from which Julia packages are drawn.
+
+  This normally points at a special augmented version of the Julia [General packages registry](https://github.com/JuliaRegistries/General). If you want to use a bleeding-edge version to pick up the latest package updates, you can plug in a later revision than the one in Nixpkgs.

nixos/doc/manual/release-notes/rl-2405.section.md

@@ -14,6 +14,8 @@ In addition to numerous new and upgraded packages, this release has the followin
    - This can be disabled through the `environment.stub-ld.enable` option.
    - If you use `programs.nix-ld.enable`, no changes are needed. The stub will be disabled automatically.
 
+- Julia environments can now be built with arbitrary packages from the ecosystem using the `.withPackages` function. For example: `julia.withPackages ["Plots"]`.
+
 ## New Services {#sec-release-24.05-new-services}
 
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