[List] reduce

lib/List.pod

@@ -217,5 +217,17 @@ If C<&by> accepts only one argument, the list elements are sorted
 according to C<< by($a) cmp by($b) >>. The return values of C<&by> are
 cached, so that C<&by> is only called once per list element.
 
+=head3 reduce
+
+    multi sub    reduce(&with, *@elems)
+    multi method reduce(List:D: &with)
+
+Applies C<&with> to the first and the second value of the list, then to result
+of that calculation and the third value and so on. Returns a single item
+generated that way.
+
+Note that C<reduce> is an implicit loop, and thus responds to C<next>, C<last>
+and C<redo> statements.
+
 
 =end pod