nixos: use shell.nix instead of cmdline args

docs/sphinx/building/user_cookbook.rst

@@ -195,9 +195,7 @@ NixOS
 .. code::
 
     # for Roc and 3rd-parties
-    $ nix-shell -p gcc autoconf automake cmake gengetopt gnumake intltool libtool meson \
-        pkg-config scons ragel \
-        libuv libunwind speexdsp sox libsndfile openssl libpulseaudio
+    $ nix-shell
 
     # clone repo
     $ git clone https://github.com/roc-streaming/roc-toolkit.git

shell.nix

@@ -0,0 +1,34 @@
+{ pkgs ? import <nixpkgs> {} }:
+
+  pkgs.mkShell {
+    buildInputs = [
+      # build deps
+      pkgs.autoconf
+      pkgs.automake
+      pkgs.clang
+      pkgs.cmake
+      pkgs.gcc
+      pkgs.gengetopt
+      pkgs.gnumake
+      pkgs.intltool
+      pkgs.libtool
+      pkgs.meson
+      pkgs.pkg-config
+      pkgs.ragel
+      pkgs.scons
+
+      # other deps
+      pkgs.libpulseaudio
+      pkgs.libsndfile
+      pkgs.libunwind
+      pkgs.libuv
+      pkgs.openssl
+      pkgs.sox
+      pkgs.speexdsp
+
+      # optional deps: formatting, tests, ...
+      pkgs.clang-tools
+      pkgs.cpputest
+      pkgs.gbenchmark
+    ];
+  }