Re: [svn:perl6-synopsis] r8609 - doc/trunk/design/syn
Larry Wall schreef: > before anyone else points it out to me > I think the long-dot > rule is built into the parser rather than falling out of the > longest-token rule. I think so too, but why then cling to the dot? s:p5/[\][#][^\]*[#][\]// (does not match \#\ ) The backslash is not (or not always) the proper character for this. s:p5/([.^\])[#].*?[#]\1/$1/ thing.# #.xFF(1,2,3) thing.\# #\xFF (0 .. ^# #^42) It's a prophet. :) -- Groet, Ruud
Re: [svn:perl6-synopsis] r8609 - doc/trunk/design/syn
On Fri, Apr 07, 2006 at 10:07:55PM +0100, Nicholas Clark wrote: : On Fri, Apr 07, 2006 at 01:11:15PM -0700, Larry Wall wrote: : > On Fri, Apr 07, 2006 at 01:04:38PM -0700, [EMAIL PROTECTED] wrote: : > : +The long dot form of the C<...> postfix is C<0. ...> rather than : > : +C<0. > because the long dot eats the first dot after the whitespace. : : > : +It does not follow that you can write C<0> because that would : > : +take the first three dots under the longest token rule. (The long dot : > : +does not count as a longer token because the longest-token rule only : > : +applies to the fixed prefix of any rule with variable components.) : > : > Yes, before anyone else points it out to me, that still doesn't quite : > make sense, insofar as the long-dot rule has to take precedence over : : What's not making sense to me is why it's not : : The long dot form of the C<...> postfix is C<0. > rather than : C<0. ...> because the long dot eats the first dot after the whitespace. : : (ie swapped the 3 and 4 dots), given that the long dot eats the first dot, : and 3 eat 1 leaves 2, whereas 4 eat 1 leaves 3. It can certainly be argued either way. It kind of depends on what you think about the first dot of '$x...' with respect to the next two dots, and whether the long dot rule ends with \. or . I tend to think of the "long dot" as a substitute for the first dot in any dotted short form, not as a prefix. To me it seems easier to teach as a "long dot" (which is dotty on both ends) than as a dot extender (which is dotty at the front and spacey at the back, but just happens to require that the next thing be a dot.) Larry
Re: [svn:perl6-synopsis] r8609 - doc/trunk/design/syn
On Fri, Apr 07, 2006 at 01:11:15PM -0700, Larry Wall wrote: > On Fri, Apr 07, 2006 at 01:04:38PM -0700, [EMAIL PROTECTED] wrote: > : +The long dot form of the C<...> postfix is C<0. ...> rather than > : +C<0. > because the long dot eats the first dot after the whitespace. > : +It does not follow that you can write C<0> because that would > : +take the first three dots under the longest token rule. (The long dot > : +does not count as a longer token because the longest-token rule only > : +applies to the fixed prefix of any rule with variable components.) > > Yes, before anyone else points it out to me, that still doesn't quite > make sense, insofar as the long-dot rule has to take precedence over What's not making sense to me is why it's not The long dot form of the C<...> postfix is C<0. > rather than C<0. ...> because the long dot eats the first dot after the whitespace. (ie swapped the 3 and 4 dots), given that the long dot eats the first dot, and 3 eat 1 leaves 2, whereas 4 eat 1 leaves 3. Nicholas Clark
Re: [svn:perl6-synopsis] r8609 - doc/trunk/design/syn
On Fri, Apr 07, 2006 at 01:04:38PM -0700, [EMAIL PROTECTED] wrote: : +The long dot form of the C<...> postfix is C<0. ...> rather than : +C<0. > because the long dot eats the first dot after the whitespace. : +It does not follow that you can write C<0> because that would : +take the first three dots under the longest token rule. (The long dot : +does not count as a longer token because the longest-token rule only : +applies to the fixed prefix of any rule with variable components.) Yes, before anyone else points it out to me, that still doesn't quite make sense, insofar as the long-dot rule has to take precedence over postfix ... if there is trailing whitespace. I think the long-dot rule is built into the parser rather than falling out of the longest-token rule. And the long-dot rule has to look ahead to see if there is whitespace following. Seems a lot more benign than the previous forms of lookahead though. Definitely easier to parse visually, I think. Larry
[svn:perl6-synopsis] r8609 - doc/trunk/design/syn
Author: larry
Date: Fri Apr 7 13:04:37 2006
New Revision: 8609
Modified:
doc/trunk/design/syn/S02.pod
Log:
More long dot cleanup.
Modified: doc/trunk/design/syn/S02.pod
==
--- doc/trunk/design/syn/S02.pod(original)
+++ doc/trunk/design/syn/S02.podFri Apr 7 13:04:37 2006
@@ -12,9 +12,9 @@
Maintainer: Larry Wall <[EMAIL PROTECTED]>
Date: 10 Aug 2004
- Last Modified: 6 Apr 2006
+ Last Modified: 7 Apr 2006
Number: 2
- Version: 20
+ Version: 21
This document summarizes Apocalypse 2, which covers small-scale
lexical items and typological issues. (These Synopses also contain
@@ -72,7 +72,9 @@
and ends with dots and contains whitespace and commentary between the dots.
The pattern for "long dot" is C<< m:p/\.+ \s \./ >>. (A minor
consequence of this is that the C<< postfix:<...> >> operator should not
-be followed by whitespace.)
+be followed by whitespace. Also, if you put space after the C<..> range
+operator, it should have space before it as well. But you already do it
+that way, right?)
For instance, if you were to add your own C<< infix:<++> >> operator,
then it must have space before it. The normal autoincrementing
@@ -111,6 +113,13 @@
But you'll have to be sure to always put whitespace in front of it, or
it would be interpreted as a postfix method call instead.)
+The long dot form of the C<...> postfix is C<0. ...> rather than
+C<0. > because the long dot eats the first dot after the whitespace.
+It does not follow that you can write C<0> because that would
+take the first three dots under the longest token rule. (The long dot
+does not count as a longer token because the longest-token rule only
+applies to the fixed prefix of any rule with variable components.)
+
=item *
Single-line comments work as in Perl 5, starting with a C<#> character
@@ -381,10 +390,11 @@
Subscripts now consistently dereference the container produced by
whatever was to their left. Whitespace is not allowed between a
variable name and its subscript. However, there is a corresponding
-B form of each subscript (C<@foo.[1]> and C<%bar.{'a'}>) which
-allows optional whitespace after the dot (except when interpolating).
-Constant string subscripts may be placed in angles, so C<%bar.{'a'}>
-may also be written as C<< %bar >> or C<< %bar. >>.
+B form of each subscript (C<@foo.[1]> and C<%bar.{'a'}>).
+There is also a "long dot" form which allows optional whitespace
+between dots. (The long dot is not allowed when interpolating). Constant
+string subscripts may be placed in angles, so C<%bar.{'a'}> may also
+be written as C<< %bar >> or C<< %bar. >>.
=item *
@@ -473,9 +483,11 @@
&foo($arg1, $arg2);
Whitespace is not allowed before the parens, but there is a corresponding
-C<.()> operator, which allows you to insert optional whitespace after the dot:
+C<.()> operator, plus a "long dot" form which allows you to insert optional
whitespace between dots:
-&foo. ($arg1, $arg2);
+&foo. .($arg1, $arg2);
+&foo... #comment
+.($arg1, $arg2);
=item *
@@ -1337,20 +1349,21 @@
(Unlike in Perl 5, where version numbers didn't autoquote.)
You can also use the :key($value) form to quote the keys of option
-pairs. To align values of option pairs, you may not use the
-dot postfix forms:
+pairs. To align values of option pairs, you may use the
+"long dot" postfix forms:
-:longkey. ($value)
-:shortkey.
-:fookey. { $^a <=> $^b }
+:longkey. .($value)
+:shortkey. .
+:fookey. .{ $^a <=> $^b }
These will be interpreted as
-:longkey(1). ($value)
-:shortkey(1).
-:fookey(1). { $^a <=> $^b }
+:longkey($value)
+:shortkey
+:fookey{ $^a <=> $^b }
-You just have to put spaces inside the parenthesis form to align things.
+But note that C<..> is not a long dot because at least one internal space
+is required to differentiate from the range operator.
=item *
