xin/templates/ocaml/flake.nix

{
  description = "thing: stuff and things";

  inputs.nixpkgs.url = "nixpkgs/nixos-23.05";

  outputs = {
    self,
    nixpkgs,
  }: let
    supportedSystems = ["x86_64-linux" "x86_64-darwin" "aarch64-linux" "aarch64-darwin"];
    forAllSystems = nixpkgs.lib.genAttrs supportedSystems;
    nixpkgsFor = forAllSystems (system: import nixpkgs {inherit system;});
  in {
    packages = forAllSystems (system: let
      pkgs = nixpkgsFor.${system};
    in {
      thing = pkgs.stdenv.mkDerivation {
        pname = "thing";
        version = "v0.0.0";
        src = ./.;
        buildInputs = with pkgs;
          [ocaml opam ocamlformat pkg-config]
          ++ (with pkgs.ocamlPackages; [dune_3 odoc]);

        buildPhase = ''
          ocamlc -o thing thing.ml
        '';

        installPhase = ''
          mkdir -p $out/bin
          mv thing $out/bin
        '';
      };
    });

    defaultPackage = forAllSystems (system: self.packages.${system}.thing);
    devShells = forAllSystems (system: let
      pkgs = nixpkgsFor.${system};
    in {
      default = pkgs.mkShell {
        shellHook = ''
          PS1='\u@\h:\@; '
          nix flake run github:qbit/xin#flake-warn
          echo "OCaml `${pkgs.ocaml}/bin/ocaml --version`"
        '';
        nativeBuildInputs = with pkgs;
          [ocaml opam ocamlformat pkg-config]
          ++ (with pkgs.ocamlPackages; [dune_3 odoc]);
      };
    });
  };
}