Finished iterating data structures.

It's not perfect, but it's there. Much of it was already covered in
the control flow document. This closes #2069.

doc/Language/iterating.pod6

@@ -123,6 +123,22 @@ C<take> and creates a list out of them.
 
 =head1 C<Classic> loops and why we do not like them
 
+Classic C<for> loops, with a loop variable being incremented, can be done in
+Perl 6 through the L<C<loop> keyword|/language/control#loop>. Other
+L<repeat|/language/control#repeat/while,_repeat/until> and
+L<while|/language/control#while,_until> loops are also possible.
+
+However, in general, they are discouraged. Perl 6 is a functional and concurrent
+language. In general, you should look at loops in a functional way: processing,
+one by one, the items produced by an interator, that is, feeding an item to a
+block without any kind of secondary effects. This functional view allows also
+easy parallelization of the operation via the L<C<hyper>|/routine/hyper> or
+L<C<race>|/routine/race> auto-threading methods.
+
+If you feel more comfortable with your good old loops, the language allows you
+to use them. However, it is considered more I<p6y> to try and use, whenever
+possible, functional and concurrent iterating constructs.
+
 =end pod
 
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