add nix build for mev-rs (and clean up devshell)

flake.nix

@@ -2,18 +2,33 @@
   description = "flake for `mev-rs` repo";
 
   inputs = {
-    nixpkgs.url = "github:NixOS/nixpkgs/nixos-unstable";
+    nixpkgs.url = "github:NixOS/nixpkgs/nixpkgs-unstable";
     flake-utils.url = "github:numtide/flake-utils";
+    rust-overlay = {
+      url = "github:oxalica/rust-overlay";
+      inputs = {
+        nixpkgs.follows = "nixpkgs";
+        flake-utils.follows = "flake-utils";
+      };
+    };
+    crane = {
+      url = "github:ipetkov/crane";
+      inputs.nixpkgs.follows = "nixpkgs";
+    };
   };
 
-  outputs = { self, flake-utils, nixpkgs }:
+  outputs = { self, flake-utils, nixpkgs, rust-overlay, crane }:
     flake-utils.lib.eachDefaultSystem
       (system:
         let
-          pkgs = import nixpkgs { inherit system; };
-          lib = pkgs.lib;
+          overlays = [ (import rust-overlay) ];
+          pkgs = import nixpkgs { inherit system overlays; };
+          rustToolchain = pkgs.pkgsBuildHost.rust-bin.fromRustupToolchainFile ./rust-toolchain.toml;
+          craneLib = (crane.mkLib pkgs).overrideToolchain rustToolchain;
+          mev = pkgs.callPackage ./nix/mev.nix { inherit pkgs; crane = craneLib; };
         in
         {
-          devShells.default = import ./shell.nix { inherit pkgs lib; };
+          packages.mev = mev;
+          devShells.default = import ./shell.nix { inherit pkgs rustToolchain; };
         });
 }

nix/mev.nix

@@ -5,10 +5,7 @@ let
     pname = "mev-rs";
     src = crane.cleanCargoSource (crane.path ../.);
     buildInputs = [ ] ++ lib.optionals pkgs.stdenv.isDarwin [
-      libiconv
-    ];
-    nativeBuildInputs = [
-      # pkgs.rustPlatform.bindgenHook
+      darwin.apple_sdk.frameworks.Network
     ];
   };
   cargoArtifacts = crane.buildDepsOnly commonArgs;

shell.nix

@@ -1,11 +1,9 @@
-{ pkgs, lib }:
+{ pkgs, rustToolchain }:
 with pkgs;
 mkShell {
-  buildInputs = lib.lists.optionals stdenv.isDarwin [
-    darwin.apple_sdk.frameworks.Network
-  ] ++ [
-    iconv
+  buildInputs = [
+    just
     mdbook
-    zlib
+    rustToolchain
   ];
 }