flake.nix

Purpose

Defines a Nix flake that provides:

• a reproducible build (nix build)
• a developer shell (nix develop) with a pinned Zig toolchain and common dev utilities

Inputs

• nixpkgs (nixos-unstable)
• zig-overlay (mitchellh/zig-overlay)

The overlay is used to select a specific Zig version when available.

System matrix

The flake defines a fixed set of supported systems:

• x86_64-linux
• aarch64-linux
• x86_64-darwin
• aarch64-darwin

Most outputs are generated for all systems using forAllSystems.

Zig pinning logic

Per system, the flake selects zigPinned as:

1. zig-overlay.packages.${system}."zig-0.15.0" if present
2. else zig-overlay.packages.${system}."0.15.0" if present
3. else pkgs.zig_0_15 if present
4. else pkgs.zig

This is intended to keep contributors on Zig 0.15.x while still providing a fallback.

packages.default

Builds a stdenvNoCC.mkDerivation that:

• sets src = ./.
• uses zig as a nativeBuildInputs
• forces Zig caches into $TMPDIR to keep Nix builds writable:
  • ZIG_GLOBAL_CACHE_DIR = "$TMPDIR/zig-cache"
  • ZIG_LOCAL_CACHE_DIR = "$TMPDIR/zig-local-cache"
• runs:
  • zig build -Doptimize=ReleaseSafe
• installs via:
  • zig build -Doptimize=ReleaseSafe -p $out

devShells.default

Provides a shell with:

• zig (pinned)
• zls
• ripgrep
• git
• nixfmt

And sets caches to repository-local directories:

• ZIG_GLOBAL_CACHE_DIR = ".zig-cache"
• ZIG_LOCAL_CACHE_DIR = ".zig-local-cache"

The shellHook prints the Zig version on entry.

formatter

Exports nixfmt as the flake formatter (preferring nixfmt-classic when present).