Author: moritz
Date: 2009-05-18 23:08:54 +0200 (Mon, 18 May 2009)
New Revision: 26876
Modified:
docs/Perl6/Spec/S02-bits.pod
docs/Perl6/Spec/S09-data.pod
Log:
[S02] get rid of the each() comprehension
[S09] document speculative each() junction with grep semantics
Modified: docs/Perl6/Spec/S02-bits.pod
===================================================================
--- docs/Perl6/Spec/S02-bits.pod 2009-05-18 18:22:24 UTC (rev 26875)
+++ docs/Perl6/Spec/S02-bits.pod 2009-05-18 21:08:54 UTC (rev 26876)
@@ -3564,32 +3564,6 @@
=item *
-When evaluating chained operators, if an C<each()> occurs anywhere in that
-chain, the chain will be transformed first into a C<grep>. That is,
-
- for 0 <= each(@x) < all(@y) {...}
-
-becomes
-
- for @x.grep:{ 0 <= $_ < all(@y) } {...}
-
-Because of this, the original ordering C<@x> is guaranteed to be
-preserved in the returned list, and duplicate elements in C<@x> are
-preserved as well. In particular,
-
- @result = each(@x) ~~ {...};
-
-is equivalent to
-
- @result = @x.grep:{...};
-
-However, this I<each() comprehension> is strictly a syntactic transformation,
-so a list computed any other way will not trigger the rewrite:
-
- @result = (@x = each(@y)) ~~ {...}; # not a comprehension
-
-=item *
-
The C<|> prefix operator may be used to force "capture" context on its
argument and I<also> defeat any scalar argument checking imposed by
subroutine signature declarations. Any resulting list arguments are
Modified: docs/Perl6/Spec/S09-data.pod
===================================================================
--- docs/Perl6/Spec/S09-data.pod 2009-05-18 18:22:24 UTC (rev 26875)
+++ docs/Perl6/Spec/S09-data.pod 2009-05-18 21:08:54 UTC (rev 26876)
@@ -1057,6 +1057,18 @@
please limit use of junctions to situations where the eventual binding
to a scalar formal parameter is clear.
+(Conjucture: in post-Perl 6.0.0 we might introduce an C<each()>
+junction which keeps track of its initial values, returning on collapse
+those initial values which transformed into a true value, for example
+
+ each(2, 3, 4) - 3
+
+would return an unordered collection consisting of 2 and 4, because
+C<2-3> and C<4-3> are True in boolean context, while C<3-3> is False.
+However it is not yet clear if we really want that, and if yes, in which
+context the collapse will occur).
+
+
=head1 Parallelized parameters and autothreading
Within the scope of a C<use autoindex> pragma (or equivalent, such as
