Author: lwall
Date: 2010-01-21 18:24:54 +0100 (Thu, 21 Jan 2010)
New Revision: 29571
Modified:
docs/Perl6/Spec/S03-operators.pod
docs/Perl6/Spec/S07-iterators.pod
Log:
[S03,S07] bring list assignment descriptions into better alignment for
pmichaud++
Modified: docs/Perl6/Spec/S03-operators.pod
===================================================================
--- docs/Perl6/Spec/S03-operators.pod 2010-01-21 13:34:35 UTC (rev 29570)
+++ docs/Perl6/Spec/S03-operators.pod 2010-01-21 17:24:54 UTC (rev 29571)
@@ -15,8 +15,8 @@
Created: 8 Mar 2004
- Last Modified: 20 Jan 2010
- Version: 184
+ Last Modified: 21 Jan 2010
+ Version: 185
=head1 Overview
@@ -2004,13 +2004,15 @@
are scalar destinations on the left or already-computed values on
the right. However, many list lvalues end with an array destination
(where assignment directly to an array can be considered a degenerate
-case). When copying into an array destination, the list assignment
-continues to copy in known values immediately, but suspends when it
-hits an actively iterating iterator (but not one merely passed as an
-object within the list). The array location on the left is then set
-up as a self-extending array, with the remainder of the list on the
-right as the "specs" for its remaining values, to be reified on
-demand. Hence it is legal to say:
+case). When copying into an array destination, the list assignment is
+"mostly eager"; it requests the list to evaluate its leading iterators
+(and values) to the extent that they are known to be finite, and
+then suspend, returning the known values. The assignment then copies
+the known values into the array. (These two steps might actually be
+interleaved depending on how the iterator API ends up being defined.)
+It then sets up the array to be self-extending by using the remainder
+of the list as the "specs" for the array's remaining values, to be
+reified on demand. Hence it is legal to say:
@natural = 0..*;
Modified: docs/Perl6/Spec/S07-iterators.pod
===================================================================
--- docs/Perl6/Spec/S07-iterators.pod 2010-01-21 13:34:35 UTC (rev 29570)
+++ docs/Perl6/Spec/S07-iterators.pod 2010-01-21 17:24:54 UTC (rev 29571)
@@ -14,8 +14,8 @@
Created: 27 Nov 2008
- Last Modified: 20 Apr 2009
- Version: 5
+ Last Modified: 21 Jan 2010
+ Version: 6
=head1 Laziness and Eagerness
@@ -87,6 +87,16 @@
will be eagerly evaluated.
+Despite the fact that "mostly eager" treats some iterators as potentially
+infinite, a list assignment to multiple targets forces evaluation (by demand)
+of enough of the list to fill any scalar destinations before a final "slurpy"
+destination. Hence:
+
+ ($a, $b, @c) = 1..*;
+
+takes the lazy iterator returned by the right side and forces it to divulge
+a C<1> and a C<2> before setting up C<@c> to mean C<3..*> lazily.
+
=item Feed operators: my @a <== @something;
The feed operator is strictly lazy, meaning that no operation should
