aarch64-darwin compatible nix

nix/shell.nix

@@ -1,4 +1,6 @@
 {
+  lib,
+  stdenv,
   mkShell,
   rustc,
   cargo,
@@ -35,15 +37,18 @@ mkShell {
     scdoc # generate man pages from doc/*.scd
   ];
 
-  buildInputs = [
-    wayland
-    wayland-protocols
-    wayland-scanner
-    libxkbcommon
-    freetype
-    fontconfig
-    harfbuzz
-  ];
+  buildInputs =
+    [
+      freetype
+      fontconfig
+      harfbuzz
+    ]
+    ++ lib.optionals stdenv.hostPlatform.isLinux [
+      wayland
+      wayland-protocols
+      wayland-scanner
+      libxkbcommon
+    ];
 
   # Compile the beer terminfo into a project-local database and put it ahead of
   # the system one, so TERM=beer resolves inside the shell (and for the shell