$Larry has just updated the pod:
doc/trunk/design/syn/S03.pod
=head1 Changes to existing operators
-If one argument is insufficiently dimensioned, Perl "upgrades" it:
+If either argument is insufficiently dimensioned, Perl "upgrades" it:
(3,8,2,9,3,8) >>-<< 1; # (2,7,1,8,2,7)
@@ -354,11 +354,26 @@
[[1, 2], 3] »+« [4, [5, 6]] # [[1,2] »+« 4, 3 »+« [5, 6]]
# == [[5, 6], [8, 9]]
+More generally, hyper operators work recursively for any object
+matching the C<Each> role even if the object itself doesn't support
+the operator in question:
+
+ Bag(3,8,[2,Seq(9,3]],8) >>-<< 1; # Bag(2,7,[1,Seq(8,2)],7)
+ Bag(3,8,[2,Seq(9,3)],8) >>-<< (1,1,1,1); # Bag(2,7,[1,Seq(8,2)],7)
+ Bag(3,8,[2,Seq(9,3)],8) >>-<< (1,1,2,1); # Bag(2,7,[2,Seq(9,3)],7)
That last one puzzles me - by this info:
-If one argument is insufficiently dimensioned, Perl "upgrades" it:
+If either argument is insufficiently dimensioned, Perl "upgrades" it:
(3,8,2,9,3,8) >>-<< 1; # (2,7,1,8,2,7)
shouldn't it be (not knowing what to do w/ Bag or Seq):
Bag(3,8,[2,Seq(9,3)],8) >>-<< (1,1,2,1); # Bag(2,7,[0,Seq(8,3)],7)
or:
Bag(3,8,[2,Seq(9,3)],8) >>-<< (1,1,2,1); # Bag(2,7,[0,Seq(7,2)],7)
(the '2' being 'upgraded to [2,2] or [2,2,2] or [2, Seq(2,2)])
+
+In particular, tree node types with C<Each> semantics enable visitation:
+
+ $tree.».foo; # short for $tree.each: {
.foo }
+
+You are not allowed to define your own hyper operators, because they
+are supposed to have consistent semantics derivable entirely from
+the modified scalar operator. If you're looking for a mathematical
+vector product, this isn't where you'll find it. A hyperoperator
+is one of the ways that you can promise to the optimizer that your
+code is parallelizable. (The tree visitation above is allowed to
+have side effects, but it is erroneous for the meaning of those side
+effects to depend on the order of visitation.)
a
Andy Bach, Sys. Mangler
Internet: [EMAIL PROTECTED]
VOICE: (608) 261-5738 FAX 264-5932
"Truth is eternal, knowledge is changeable.
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-- Madeleine L'Engle
