Note @A».say; as being an error

Author: zoffixznet

doc/Language/operators.pod6

@@ -585,11 +585,15 @@ X<|postfix ».>
 X<Hyper method call operator>. Will call a method on all elements of a C<List> out of order and return the list of return values in order.
 
     my @a = <a b c>;
-    @a».say;                          # a␤b␤c␤
     my @b = @a».ord;                  # [97, 98, 99]
     sub foo(Str:D $c){ $c.ord * 2 };  # The first parameter of a method is the invocant.
     say @a».&foo;                     # So we can pretend to have a method call with a sub that got a good first positional argument.
-    say @a».&{ .ord};               # Blocks have an implicit positional arguments that lands in $_. The latter can be omitted for method calls.
+    say @a».&{ .ord};                 # Blocks have an implicit positional arguments that lands in $_. The latter can be omitted for method calls.
+
+Take care to avoid a common mistake of expecting side-effects to occur in order. The following
+C<say> is B<not> guaranteed to produce the output in order:
+
+    @a».say;  # WRONG! Could produce a␤b␤c␤ or c␤b␤a␤ or any other order
 
 =head2 postfix C<.postfix> / C<.postcircumfix>
 X<|.( )>X<|.[ ]>X<|.{ }>