Fix flake for OSX

The prover deps are now optional, making this flake usable to build a simulator.

book/getting_started/install.md

@@ -14,6 +14,21 @@
 sudo apt-get install -y xz-utils jq curl git build-essential qemu-system libomp-dev libgmp-dev nlohmann-json3-dev protobuf-compiler uuid-dev libgrpc++-dev libsecp256k1-dev libsodium-dev libpqxx-dev nasm
 ```
 
+### Nix Flake
+
+Alternatively, you can use [Nix package manager](https://github.com/NixOS/nix) to install all dependencies. First, follow the [guite to install Nix](https://determinate.systems/nix/) on your OS.
+
+Afterwards, use `flake.nix` in `zisk` repository to load the development environment with:
+```
+nix develop
+
+# You can also use a custom shell: 
+nix develop -c zsh
+```
+
+This will start a new shell with correctly set `PATH` and `LD_LIBRARY_PATH` for dependencies necessary to build the project.
+You can exit this shell with Ctrl+D.
+
 ### OSX prerequisites
 ```bash
 # Install brew first.

book/getting_started/quickstart.md

@@ -130,7 +130,7 @@ cd zisk
 
 ### Compile the PIl2 Stark C++ Library (run only once):
 ```bash
-(cd ../pil2-proofman/pil2-stark && git submodule init && git submodule update && make clean && make -j starks_lib && make -j bctree) && export RUSTFLAGS="-L native=$PWD/../pil2-proofman/pil2-stark/lib"
+(cd ../pil2-proofman/pil2-stark && git submodule init && git submodule update && make clean && make -j starks_lib && make -j bctree) && export RUSTFLAGS=$RUSTFLAGS" -L native=$PWD/../pil2-proofman/pil2-stark/lib"
 ```
 
 ### Generate PIL-Helpers Rust Code
@@ -164,4 +164,4 @@ To generate the proof, the following command needs to be run.
 ```bash
 (cd ../pil2-stark-js && npm i) 
 node ../pil2-stark-js/src/main_verifier.js -v build/provingKey/zisk/final/final.verkey.json -s build/provingKey/zisk/final/final.starkinfo.json -i build/provingKey/zisk/final/final.verifierinfo.json -o proofs/proofs/final_proof.json -b proofs/publics.json
-```
+```

flake.nix

@@ -0,0 +1,41 @@
+{
+  description = "A flake with project build dependencies";
+  inputs.nixpkgs.url = "github:NixOS/nixpkgs/nixpkgs-unstable";
+  inputs.systems.url = "github:nix-systems/default";
+  inputs.flake-utils = {
+    url = "github:numtide/flake-utils";
+    inputs.systems.follows = "systems";
+  };
+
+  outputs = { self, nixpkgs, flake-utils, ... }:
+    flake-utils.lib.eachDefaultSystem (system:
+      let
+        pkgs = import nixpkgs {
+          inherit system;
+          config.allowUnfreePredicate = pkg:
+            builtins.elem (nixpkgs.lib.getName pkg) [ "mkl" ];
+        };
+      in {
+        devShells.default = pkgs.mkShell {
+          packages = [
+            pkgs.grpc
+            pkgs.gmp
+            pkgs.jq
+            pkgs.libsodium
+            pkgs.libpqxx
+            pkgs.libuuid
+            pkgs.openssl
+            pkgs.postgresql
+            pkgs.protobuf
+            pkgs.secp256k1
+            pkgs.nlohmann_json
+            pkgs.nasm
+            pkgs.libgit2
+          ] ++ (pkgs.lib.optionals pkgs.stdenv.isLinux [ pkgs.mkl ])
+            ++ (pkgs.lib.optionals pkgs.stdenv.isDarwin
+              [ pkgs.darwin.apple_sdk.frameworks.Security ]);
+
+          RUSTFLAGS = (builtins.map (a: "-L ${a}/lib") [ pkgs.libgit2 ]);
+        };
+      });
+}