Replace the elegant List.perl implementation that trips up ng somehow…

… with an ugly one that works.

src/core/List.pm

@@ -1,6 +1,12 @@
 augment class List {
     method perl() {
-        '(' ~ self.map({ $_.perl }).join(', ') ~ ')';
+        # '(' ~ self.map({ $_.perl }).join(', ') ~ ')';
+        my $result = "(";
+        for self -> $x {
+            $result ~= ", " if $result.chars > 1;
+            $result ~= $x.perl;
+        }
+        return $result ~ ")";
     }
 }