Using Nix Develop Environment#

Install nix from shell#

sh <(curl -L https://nixos.org/nix/install) --daemon

then exec bash -l reload your bash to load the nix-env

Enable Flake Feature Of Nix#

echo "experimental-features = nix-command flakes" | sudo tee -a /etc/nix/nix.conf
sudo pkill nix-daemon

NOTE: reload bash and check your nix-version first

nix --version
nix (Nix) 2.4

Nix flake feature already in emacsNg#

nix run github:emacs-ng/emacs-ng (launch emacs locally )
nix build github:emacs-ng/emacs-ng (build emacs locally)
nix develop github:emacs-ng/emacs-ng (enter develop emacs environment locally)

Also, you can run native nix commands (Nix Stable Version) under emacs-ng repo, such as

nix-shell
nix-build

Using `cachix` to (download binary cache) speed up build#

Without installing cachix

nix build github:emacs-ng/emacs-ng --option substituters "https://emacsng.cachix.org" --option trusted-public-keys "emacsng.cachix.org-1:i7wOr4YpdRpWWtShI8bT6V7lOTnPeI7Ho6HaZegFWMI=" -o emacsNg
ls -il emacs
#or check ./result/bin/emacs
nix-build --option substituters "https://emacsng.cachix.org" --option trusted-public-keys "emacsng.cachix.org-1:i7wOr4YpdRpWWtShI8bT6V7lOTnPeI7Ho6HaZegFWMI="

Installing cachix

nix-env -iA cachix -f https://cachix.org/api/v1/install #install cachix
exec bash -l
cachix use emacsng # make sure you have saw the output like: Configured https://emacsng.cachix.org binary cache in /home/test/.config/nix/nix.conf
#then
nix-build
#or
nix build github:emacs-ng/emacs-ng -o emacsNG
ls -il emacsNG

Clone Emacs Ng By Nix-Shell And Enable Emacs Cachix#

nix-env -iA cachix -f https://cachix.org/api/v1/install
exec bash -l
cachix use emacsng # make sure you have saw the output like: Configured https://emacsng.cachix.org binary cache in /home/test/.config/nix/nix.conf
nix-shell -p git --command "git clone https://github.com/emacs-ng/emacs-ng.git && cd emacs-ng && nix-shell"

Setting Up Rust Development Environment#

Change Rust Version#

Nightly Version
located nix/rust.nix modify the 2021-01-14to which your want.(rustOverlay-NightlyCheck) Example: default = pkgs.rust-bin.nightly."2021-03-23";
Stable version
example : default = pkgs.rust-bin.stable."1.50.0"; (rustOverlay-StableCheck)
Beta version
example : default = pkgs.rust-bin.beta."2021-03-06"; (rustOverlay-StableCheck)

Add Package from RustOverly#

The RustOverly supported Packages list that you can find here (packages-list)

located nix/rust.nix

    rustOverlaySet = mkOption {
      type = types.listOf types.str;
      default = [
        "rustc"
        "cargo"
        "rustfmt-preview"
        "<add other package which you can found in package-list>"
      ];
      description = "Which rust tools to pull from the rust overlay
      https://github.com/oxalica/rust-overlay/blob/master/manifests/profiles.nix";
    };

Add rustPackages from nixpkgs channel#

located nix/rust.nix and the default nix expression like this rustPackages.clippy. In this cause, most of rust toolchain installed from rustOverly

    rustPackagesSet = mkOption {
      type = types.listOf types.str;
      default = [
        "clippy"
        "<add custom Rust toolchain package>"
      ];
      description = "Which rust tools to pull from the nixpkgs channel package set
      check valid package from https://search.nixos.org/packages?channel=unstable";
      ";
    };

Add nixpkgs package to current Environment#

located nix/rust.nix

first, search for package in search-package then add the name of package to:

devshell.packages = map (tool: cfg.rustPackages.${tool}) cfg.rustPackagesSet
      ++ map (tool: cfg.rustOverlay.${tool}) cfg.rustOverlaySet ++ (with pkgs;[
      #custom nixpkgs packages
      rustracer
      <add package here>
    ]);
 ```

## Reload all of environments when you changed something

- normally, we can re-enter `nix-shell` to reload environments. But for this project, we are using direnv to load and unload environment variables in an convenient way.

### Recommended Way -> Direnv

 Install direnv by Nix

    nix-env -i direnv

and hook direnv to your bash [direnv-hook](https://direnv.net/docs/hook.html)

- using `direnv allow`  or `direnv deny` to enable or disable load `nix-shell` in current path

- using `direnv reload` to reload `nix-shell`

- Also, you can put as follows to `~/.config/direnv/direnvrc` watching the envrs every time changes that could be reload automatically.


```bash
use_flake() {
  watch_file flake.nix
  watch_file flake.lock
  eval "$(nix print-dev-env)"
}

Add Direnv Support With Emacs#

https://github.com/purcell/envrc

Install direnv to Doom Emacs, Example

(package! envrc :recipe (:host github :repo "purcell/envrc"))
(use-package! envrc
:hook (after-init . envrc-global-mode)
)

then M-x typing envrv-<**> check related commands similar to native direnv-commands

Write A Custom Command Or Environment Variable#

locaed nix/commands.toml
Add custom command as following: Example

[[commands]]
name = ""
command = "cargo build --manifest-path=./crates/codegen/Cargo.toml"
help = "cargo build codegen"
category = "rust-build"

Add custom env variable as following:

[[env]]
name = "TEST"
vale = "/bin/test"
#prefix = "$( cd "$(dirname "$\{\BASH_SOURCE [ 0 ]}")"; pwd )" can be prefix

Building Emacs-ng in development mode#

located flake.nix commented emacsNG-src to "./."

Example:

        let
          #emacsNgSource = emacsNG-src;
          emacsNgSource = "./.";
        in

then nix-build it;

Add custom configFlags to emacsNg build process#

located flake.nix

configureFlags = (old.configureFlags or [ ]) ++ [
        "--with-json"
        "--with-threads"
        "--with-included-regex"
        "--with-harfbuzz"
        "--with-compress-install"
        "--with-zlib"
        "<custom flags>"
];

NOTICE: nix-build action in sandbox mode. If you want to modify something or patch it, please put it this way to the corresponding step.

For example:

preConfigure = (old.preConfigure or "") + ''
  <modify shell>
            '';

patches = (old.patches or [ ]) ++ [
./nix/<your-pathc-file.patch>
];

if everything looks good, you can run nix-build right now.

Last update: April 24, 2024