added nix flake for shell

flake.lock

@@ -0,0 +1,44 @@
+{
+  "nodes": {
+    "nixpkgs": {
+      "locked": {
+        "lastModified": 1647122627,
+        "narHash": "sha256-w4hGsXYyMgJAQRSBxh7O6AAsawJSbudCxfQXhDRhwPQ=",
+        "owner": "nixos",
+        "repo": "nixpkgs",
+        "rev": "0f85665118d850aae5164d385d24783d0b16cf1b",
+        "type": "github"
+      },
+      "original": {
+        "owner": "nixos",
+        "ref": "nixos-21.11",
+        "repo": "nixpkgs",
+        "type": "github"
+      }
+    },
+    "nixpkgs-unstable": {
+      "locked": {
+        "lastModified": 1647199004,
+        "narHash": "sha256-37aHbLhcX6zqeru24AoPPfem6fUQ6are5E38NdbIgJg=",
+        "owner": "NixOS",
+        "repo": "nixpkgs",
+        "rev": "328bd3c30e4fc4c3d69bc08516f27e8d85f839b6",
+        "type": "github"
+      },
+      "original": {
+        "owner": "NixOS",
+        "ref": "nixpkgs-unstable",
+        "repo": "nixpkgs",
+        "type": "github"
+      }
+    },
+    "root": {
+      "inputs": {
+        "nixpkgs": "nixpkgs",
+        "nixpkgs-unstable": "nixpkgs-unstable"
+      }
+    }
+  },
+  "root": "root",
+  "version": 7
+}

flake.nix

@@ -0,0 +1,70 @@
+{
+  description = "Roc flake";
+
+  inputs = {
+    nixpkgs.url = "github:nixos/nixpkgs/nixos-21.11";
+    nixpkgs-unstable = { url = "github:NixOS/nixpkgs/nixpkgs-unstable"; };
+    # zig = { url = "github:roarkanize/zig-overlay"; };
+  };
+
+  outputs = { self, nixpkgs, nixpkgs-unstable }:
+    let
+      pkgs = nixpkgs.legacyPackages.x86_64-linux;
+      unstable-pkgs = nixpkgs-unstable.legacyPackages.x86_64-linux;
+      llvmPkgs = pkgs.llvmPackages_12;
+
+      linuxInputs = with pkgs; [
+        valgrind # used in cli tests, see cli/tests/cli_run.rs
+        vulkan-headers
+        vulkan-loader
+        vulkan-tools
+        vulkan-validation-layers
+        xorg.libX11
+        xorg.libXcursor
+        xorg.libXrandr
+        xorg.libXi
+        xorg.libxcb
+        alsa-lib
+      ];
+
+      sharedInputs = (with pkgs; [
+        # build libraries
+        cmake
+        git
+        python3
+        llvmPkgs.llvm.dev
+        llvmPkgs.clang
+        libxkbcommon
+        pkg-config
+        zig # roc builtins are implemented in zig, see compiler/builtins/bitcode/
+
+        # lib deps
+        libffi
+        libxml2
+        ncurses
+        zlib
+        libiconv
+
+        # faster builds - see https://github.com/rtfeldman/roc/blob/trunk/BUILDING_FROM_SOURCE.md#use-lld-for-the-linker
+        llvmPkgs.lld
+        # debugir
+      ]) ++ (with unstable-pkgs; [
+        rustc
+        cargo
+        clippy
+        rustfmt
+      ]);
+    in {
+
+      devShell.x86_64-linux = pkgs.mkShell {
+        buildInputs = sharedInputs ++ linuxInputs;
+
+        LLVM_SYS_120_PREFIX = "${llvmPkgs.llvm.dev}";
+        NIX_GLIBC_PATH = if pkgs.stdenv.isLinux then "${pkgs.glibc_multi.out}/lib" else "";
+        LD_LIBRARY_PATH = with pkgs;
+          lib.makeLibraryPath
+          ([ pkg-config stdenv.cc.cc.lib libffi ncurses zlib ] ++ linuxInputs);
+      };
+
+    };
+}