switch to flake

flake.nix

@@ -0,0 +1,30 @@
+{
+  description = "vector";
+
+  inputs = {
+    nixpkgs.url = "github:NixOS/nixpkgs/master";
+    flake-utils.url = "github:numtide/flake-utils";
+  };
+
+  outputs = { self, nixpkgs, flake-utils }@inputs:
+    let
+      overlay = import ./overlay.nix;
+    in
+    flake-utils.lib.eachDefaultSystem
+      (system:
+        let
+          pkgs = import nixpkgs { inherit system; overlays = [ overlay ]; };
+          deps = with pkgs; [
+            mill
+            espresso
+          ];
+        in
+        {
+          legacyPackages = pkgs;
+          devShell = pkgs.mkShell {
+            buildInputs = deps;
+          };
+        }
+      )
+    // { inherit inputs; overlays.default = overlay; };
+}

nix/espresso.nix

@@ -0,0 +1,13 @@
+{ stdenv, fetchFromGitHub, cmake, ninja }:
+stdenv.mkDerivation rec {
+  pname = "espresso";
+  version = "2.4";
+  nativeBuildInputs = [ cmake ninja ];
+  src = fetchFromGitHub {
+    owner = "chipsalliance";
+    repo = "espresso";
+    rev = "v${version}";
+    sha256 = "sha256-z5By57VbmIt4sgRgvECnLbZklnDDWUA6fyvWVyXUzsI=";
+  };
+}
+

overlay.nix

@@ -0,0 +1,5 @@
+final: prev:
+{
+  mill = prev.mill.override { jre = final.openjdk19; };
+  espresso = final.callPackage ./nix/espresso.nix { };
+}