Add a note on adapting content for darwin

pills/08-generic-builders.xml

@@ -48,6 +48,12 @@
     </para>
 
     <screen><xi:include href="./08/hello-nix.txt" parse="text" /></screen>
+    <sidebar><title>Nix on darwin</title>
+    <para>The darwin (i.e. macOS) <literal>stdenv</literal> diverges from the Linux <literal>stdenv</literal> in several ways. A main difference is that the darwin <literal>stdenv</literal> relies upon <literal>clang</literal> rather than <literal>gcc</literal> as its C compiler. We can adapt this early example of how a <literal>stdenv</literal> works for darwin by using this modified version of <filename>hello.nix</filename>:
+    </para>
+    <screen><xi:include href="./08/hello-nix-darwin.txt" parse="text" /></screen>
+    Please be aware that similar changes may be needed in what follows.
+    </sidebar>
 
     <para>
       Now build it with <command>nix-build hello.nix</command> and you can

pills/08/hello-nix-darwin.txt

@@ -0,0 +1,11 @@
+with (import <nixpkgs> {});
+derivation {
+  name = "hello";
+  builder = "${bash}/bin/bash";
+  args = [ ./hello_builder.sh ];
+  inherit gnutar gzip gnumake coreutils gawk gnused gnugrep;
+  gcc = clang;
+  binutils_unwrapped = clang.bintools.bintools_bin;
+  src = ./hello-2.10.tar.gz;
+  system = builtins.currentSystem;
+}

style.css

@@ -266,3 +266,14 @@ table.simplelist
 div.navheader table, div.navfooter table {
     box-shadow: none;
 }
+
+div.sidebar
+{
+    float: right;
+    margin: 1em 5%;
+    padding: 10px;
+    border: 2px dashed #b0b0b0;
+    border-radius: 0.4em;
+    background: #f8f8fc;
+    box-shadow: 0.4em 0.4em 0.5em #e0e0e0;
+}