{

inputs = {

nixpkgs.url = "github:nixos/nixpkgs/release-24.11";

# cross-platform convenience

flake-utils.url = "github:numtide/flake-utils";

# backwards compatibility with nix-build and nix-shell

flake-compat.url = "https://flakehub.com/f/edolstra/flake-compat/1.tar.gz";

};

outputs = { self, nixpkgs, flake-utils, flake-compat }:

# resolve for all platforms in turn

flake-utils.lib.eachDefaultSystem (system:

let

# packages for this system platform

pkgs = nixpkgs.legacyPackages.${system};

# control versions

ruby = pkgs.ruby_3_4;

llvm = pkgs.llvmPackages_19;

gcc = pkgs.gcc14;

hook = ''

# get major.minor.0 ruby version

export RUBY_VERSION="$(ruby -e 'puts RUBY_VERSION.gsub(/\d+$/, "0")')"

# make gem install work in-project, compatibly with bundler

export GEM_HOME="$(pwd)/vendor/bundle/ruby/$RUBY_VERSION"

# make bundle work in-project

export BUNDLE_PATH="$(pwd)/vendor/bundle"

# enable calling gem scripts without bundle exec

export PATH="$GEM_HOME/bin:$PATH"

# enable implicitly resolving gems to bundled version

export RUBYGEMS_GEMDEPS="$(pwd)/Gemfile"

'';

deps = [

pkgs.libyaml.dev

# TODO: some gems insist on using `gcc` on Linux, satisfy them for now:

# - json

# - protobuf

# - ruby-prof

gcc

];

in {

devShells.default = llvm.stdenv.mkDerivation {

name = "devshell";

buildInputs = [ ruby ] ++ deps;

shellHook = hook;

};

devShells.ruby33 = llvm.stdenv.mkDerivation {

name = "devshell";

buildInputs = [ pkgs.ruby_3_3 ] ++ deps;

shellHook = hook;

};

devShells.ruby32 = llvm.stdenv.mkDerivation {

name = "devshell";

buildInputs = [ pkgs.ruby_3_2 ] ++ deps;

shellHook = hook;

};

devShells.ruby31 = llvm.stdenv.mkDerivation {

name = "devshell";

buildInputs = [ pkgs.ruby_3_1 ] ++ deps;

shellHook = hook;

};

}

);

}