Add initial flake.nix; flake.lock

flake.nix

@@ -0,0 +1,37 @@
+{
+  description = "proof-system prerequisites";
+
+  inputs = {
+    naersk.url = "github:nix-community/naersk/master";
+    nixpkgs.url = "github:NixOS/nixpkgs/nixpkgs-unstable";
+    utils.url = "github:numtide/flake-utils";
+  };
+
+  outputs = { self, nixpkgs, utils, naersk }:
+    utils.lib.eachDefaultSystem (system:
+      let
+        pkgs = import nixpkgs { inherit system; };
+        naersk-lib = pkgs.callPackage naersk { };
+      in
+      {
+        defaultPackage = naersk-lib.buildPackage ./.;
+        devShell = with pkgs; mkShell {
+          buildInputs = [
+            # rust inputs
+            rustup
+            rust-analyzer
+            libiconv # Needed for macOS for rustup
+
+            # ocaml inputs
+            opam
+
+            # go inputs
+            gopls
+            go
+
+          ];
+          RUST_SRC_PATH = rustPlatform.rustLibSrc;
+        };
+      }
+    );
+}