prefer chez scheme 10+ over racket fork (#3233)

INSTALL.md

@@ -54,9 +54,12 @@ make sure you run `./configure --threads` to build multithreading support in.
 **NOTE**: On FreeBSD, OpenBSD and NetBSD you need to use `gmake` command instead
 of `make` in the following steps.
 
-**NOTE**: If you're running macOS on Apple Silicon (arm64) you will need to
-install the Racket fork of chez scheme as described below.  If you install gmp
-via homebrew, you will also need to `export CPATH=/opt/homebrew/include`.
+**NOTE**: If you're running macOS on Apple Silicon (arm64) you will need to use
+Chez scheme version `10.0.0` or greater. Homebrew has been updated to ship Chez
+Scheme 10+ as of this writing. If you cannot install Chez Scheme 10+, install
+the Racket fork of chez scheme as described
+[below](#installing-chez-scheme-on-apple-silicon). If you install gmp via
+homebrew, you will also need to `export CPATH=/opt/homebrew/include`.
 
 ### 1: Set installation target directory
 
@@ -194,17 +197,17 @@ nix run github:idris-lang/Idris2#emacs-with-idris idrisCode.idr
 
 ## Installing Chez Scheme on Apple Silicon
 
-The official version of chez scheme does not yet support Apple Silicon. So, on
-macOS with Apple Silicon (e.g. M1 and M2 macs), you will need to build and install
-the Racket fork of chez scheme.
+Chez scheme only supports Apple Silicon for versions `10.0.0` or newer.
+
+Homebrew bundles Chez Scheme 10+ so if that's your manager of choice, you don't
+need to read on.
+
+If you cannot install that new of a version of Chez Scheme, you will need to
+build and install the Racket fork of chez scheme.
 
 ```sh
 git clone git@github.com:racket/ChezScheme.git
 cd ChezScheme
-git submodule init
-git submodule update
-./configure --pb
-make tarm64osx.bootquick
 ./configure --threads
 make
 sudo make install

flake.nix

@@ -28,10 +28,12 @@
         system:
         let
           pkgs = import nixpkgs { inherit config system overlays; };
-          chez = if system == "x86_64-linux" then
+          chezSupportsSystem = (system == "x86_64-linux")
+            || (pkgs.lib.versionAtLeast pkgs.chez.version "10.0.0");
+          chez = if chezSupportsSystem then
             pkgs.chez
           else
-            pkgs.chez-racket; # TODO: Should this always be the default?
+            pkgs.chez-racket;
           idris2Support = pkgs.callPackage ./nix/support.nix { inherit idris2Version; };
           idris2Bootstrap = pkgs.callPackage ./nix/package.nix {
             inherit idris2Version chez;