Attempt to make Inline::Python optional

... falling back to the old shelling-out code

htmlify.p6

@@ -13,7 +13,6 @@ use Perl6::TypeGraph;
 use Perl6::TypeGraph::Viz;
 use Perl6::Documentable::Registry;
 use Pod::Convenience;
-use Inline::Python;
 
 my $*DEBUG = False;
 
@@ -710,8 +709,10 @@ sub pygmentize-code-blocks {
         return;
     }
 
-    my $py = Inline::Python.new();
-    $py.run(q{
+    my $py = try {
+        require Inline::Python;
+        my $py = ::('Inline::Python').new();
+        $py.run(q{
 import pygments.lexers
 import pygments.formatters
 p6lexer = pygments.lexers.get_lexer_by_name("perl6")
@@ -720,6 +721,11 @@ htmlformatter = pygments.formatters.get_formatter_by_name("html")
 def p6format(code):
     return pygments.highlight(code, p6lexer, htmlformatter)
 });
+        $py;
+    }
+    if defined $py {
+        say "Using syntax hilight using Inline::Python";
+    }
 
     %*POD2HTML-CALLBACKS = code => sub (:$node, :&default) {
         for @($node.contents) -> $c {
@@ -728,7 +734,18 @@ def p6format(code):
                 return default($node);
             }
         }
-        return $py.call('__main__', 'p6format', $node.contents.join);
+        if defined $py {
+            return $py.call('__main__', 'p6format', $node.contents.join);
+        }
+        else {
+            my $basename = join '-', %*ENV<USER> // 'u', (^100_000).pick, 'pod_to_pyg.pod';
+            my $tmp_fname = "$*TMPDIR/$basename";
+            spurt $tmp_fname, $node.contents.join;
+            LEAVE try unlink $tmp_fname;
+            my $command = "pygmentize -l perl6 -f html < $tmp_fname";
+            return qqx{$command};
+
+        }
     }
 }