[svn:perl6-synopsis] r14413 - doc/trunk/design/syn
Author: larry
Date: Sat Jun 2 12:42:11 2007
New Revision: 14413
Modified:
doc/trunk/design/syn/S02.pod
doc/trunk/design/syn/S03.pod
doc/trunk/design/syn/S04.pod
doc/trunk/design/syn/S06.pod
doc/trunk/design/syn/S09.pod
doc/trunk/design/syn/S13.pod
Log:
Dropped : from all listop contextualizers, whether sigil and typename.
The @@ contextualizer is now also named "slice".
Consistent with that, we have regularized slice nomenclature:
* A "slice" now always refers to the whole multidimensional subscript,
or the list of lists corresponding to that.
* We now try to avoid calling the individual sublists "slices".
* The parameter to a subscript is *@@slice, not *@@slices.
* The term "multislice" is now deemed redundant.
Modified: doc/trunk/design/syn/S02.pod
==
--- doc/trunk/design/syn/S02.pod(original)
+++ doc/trunk/design/syn/S02.podSat Jun 2 12:42:11 2007
@@ -12,9 +12,9 @@
Maintainer: Larry Wall <[EMAIL PROTECTED]>
Date: 10 Aug 2004
- Last Modified: 29 May 2007
+ Last Modified: 2 Jun 2007
Number: 2
- Version: 108
+ Version: 109
This document summarizes Apocalypse 2, which covers small-scale
lexical items and typological issues. (These Synopses also contain
@@ -446,8 +446,11 @@
$spot.defined; # False
say $spot; # "Dog"
-Any class name used as a value by itself is an undefined instance of that
-class's prototype. See S12 for more on that.
+Any class name used as a value by itself is an undefined instance of
+that class's prototype, or I. See S12 for more on that.
+(Any type name in rvalue context is parsed as a list operator
+indicating a typecast, but an argumentless one of these degenerates
+to a typecast of undef, producing the protoobject.)
To get a real C object, call a constructor method such as C:
@@ -1059,7 +1062,7 @@
% unordered hash (associative array)
& code/rule/token/regex
:: package/module/class/role/subset/enum/type/grammar
-@@ multislice view of @
+@@ slice view of @
Within a declaration, the C<&> sigil also declares the visibility of the
subroutine name without the sigil within the scope of the declaration:
@@ -1324,9 +1327,9 @@
=item *
-Slicing syntax is covered in S09. Multidimensional
-slices will be done with semicolons between individual slice subscripts.
-Each such slice is evaluated lazily.
+Slicing syntax is covered in S09. A multidimensional
+slice will be done with semicolons between individual slice sublists.
+Each such slice sublist is evaluated lazily.
=item *
@@ -1422,9 +1425,17 @@
than a punctuational variable. This allows you to use sigils as coercion
operators:
-print $( foo() )
+print $( foo() )# foo called in item context
+print @@( foo() ) # foo called in slice context
-It also allows the use of bare sigils as placeholders for anonymous variables:
+The bare sigil is parsed as a list operator in rvalue context, so
+these mean the same thing:
+
+print $ foo() # foo called in item context
+print @@ foo() # foo called in slice context
+
+In declarative contexts bare sigils may be used as placeholders for
+anonymous variables:
my ($a, $, $c) = 1..3;
print unless (state $)++;
Modified: doc/trunk/design/syn/S03.pod
==
--- doc/trunk/design/syn/S03.pod(original)
+++ doc/trunk/design/syn/S03.podSat Jun 2 12:42:11 2007
@@ -12,9 +12,9 @@
Maintainer: Larry Wall <[EMAIL PROTECTED]>
Date: 8 Mar 2004
- Last Modified: 29 May 2007
+ Last Modified: 2 Jun 2007
Number: 3
- Version: 115
+ Version: 116
=head1 Overview
@@ -729,16 +729,6 @@
Note that, unlike in Perl 5, you must use the C<.meth> forms to default
to C<$_> in Perl 6.
-=item *
-
-The C contextualizer
-
-item
-
-The new name for Perl 5's C contextualizer. Equivalent to C<$()>.
-We still call the values scalars, and talk about "scalar operators", but
-scalar operators are those that put their arguments into item context.
-
=back
=head2 Nonchaining binary precedence
@@ -1297,40 +1287,80 @@
Sigils as contextualizer listops
-$:
-@:
-%:
-&:
-@@:
+Sigil Alpha variant
+- -
+$ item
+@ list
+@@ slice
+% hash
As listops, these look like terms from the left, but raise their
precedence on the right sufficiently to govern list infix
operators:
- $: 1,2 Z 3,4 # [[1,3],[2,4]]
- @: 1,2 Z 3,4 # 1,3,2,4
-@@: 1,2 Z 3,4 # [1,3],[2,4]
- %: 1,2 Z 3,4 # { 1 => 3, 2 => 4 }
-
- $: 1,2 X 3,4 # [[1,3],[1,4],[2,3],[2,4]]
- @: 1,2 X 3,4 # 1,3,1,4,2,3,2,4
-@@: 1,2 X 3,4 # [1,3],[1,4],[2,3],[2,4]
+ $ 1,2 Z 3,4 # [\(1,3),\(2,4)]
+ @ 1,2 Z 3,4 # 1,3,2,4
+@@ 1,
[svn:perl6-synopsis] r14414 - doc/trunk/design/syn
Author: larry
Date: Sat Jun 2 14:45:43 2007
New Revision: 14414
Modified:
doc/trunk/design/syn/S03.pod
Log:
First installment of filling out descriptions of operator semantics.
Modified: doc/trunk/design/syn/S03.pod
==
--- doc/trunk/design/syn/S03.pod(original)
+++ doc/trunk/design/syn/S03.podSat Jun 2 14:45:43 2007
@@ -97,21 +97,40 @@
=item *
+Heredoc
+
+qq:to/END/
+Dear $recipient:
+Thanks!
+Sincerely,
+$me
+END
+
+=item *
+
Array composer
[1,2,3]
+Provides list context inside.
+
=item *
Hash composer
{ a => 42 }
+Inside must be a list of pairs, otherwise you must use C
+or C<%()> instead.
+
=item *
Closure
-{...}
+{ ... }
+
+When found where a statement is expected, executes immediately. Othewise
+always defers evaluation of the inside scope.
=item *
@@ -119,6 +138,8 @@
\(@a,$b,%c)
+An abstraction representing an argument list that doesn't yet know its context.
+
=item *
Sigiled variables
@@ -128,7 +149,7 @@
%z
$^a
$?FILE
-@@multidim
+@@slice
&func
&div:(Int, Int --> Int)
@@ -247,6 +268,9 @@
$obj.::Class::meth
$obj.Class::meth# same thing, assuming Class is predeclared
+As in Perl 5, tells the dispatcher which class to start searching from,
+not the exact method to call.
+
=item *
Mutating method call
@@ -286,7 +310,7 @@
Dotted postfix form of any other prefix operator
-$x.'++' # prefix:<++>($x), fallback to postfix:<++>
+$x.:<++> # prefix:<++>($x)
=back
@@ -396,79 +420,109 @@
prefix:, boolean context
-?
+?$x
+Evaluates the expression as a boolean and returns C if expression
+is true or C otherwise.
See "true" below for a low-precedence alternative.
=item *
prefix:, boolean negation
-!
+!$x
+Returns the opposite of what C would.
See "not" below for a low-precedence alternative.
=item *
prefix:<+>, numeric context
-+
++$x
+
+Unlike in Perl 5, where C<+> is a no-op, this operator coerces
+to numeric context in Perl 6. (It coerces only the value, not the
+original variable.) The narrowest appropriate type of C, C,
+or C will be returned. A string containing two integers
+separated by a C will be returned as a C. Exponential notation
+and radix notations are recognized.
=item *
prefix:<->, numeric negation
--
+-$x
+
+Coerces to numeric and returns the negation of the resulting number.
=item *
prefix:<~>, string context
-~
+~$x
+
+Coerces the value to a string. (It only coerces the value, not the
+original variable.)
=item *
prefix:<|>, flatten object into arglist
-|
+| $capture
+
+Interpolates the contents of the C (or C-like) value
+into the current argument list as if they had been specified literally.
=item *
prefix:<+^>, numeric bitwise negation
-+^
++^$x
+
+Coerces to numeric and then does bitwise negation on the number.
=item *
prefix:<~^>, string bitwise negation
-~^
+~^$x
+Coerces to string buffer and then does bitwise negation on each element.
=item *
prefix:, boolean bitwise negation
-?^
+?^$x
+
+Coerces to boolean and then flips the bit. (Same as C.)
=item *
prefix:<\>, Capture constructor
-\
+\$x
+[EMAIL PROTECTED]
+\%x
+\($invocant: $pos1, $pos2, :named($arg))
+
+Defers the contextualization of its argument or arguments till it is
+bound into some other context.
=item *
prefix:<^>, upto operator
-^
+^$limit
-Constructs a range or locates a metaclass. See L.
+Constructs a range of C<0..^$limit> or locates a metaclass as a shortcut
+for C<$limit.HOW>. See L.
=item *
prefix:<=>, iterate iterator
-=
+=$iterator
Unary C<=> reads lines from a filehandle or filename, or
iterates an iterator, or in general causes a scalar to explode its guts
@@ -491,7 +545,9 @@
infix:<*>
-*
+$x*$y
+
+Multiplication, resulting in wider type of the two.
=item *
@@ -499,7 +555,8 @@
$numerator / $denominator
-Converts both operands to C and does division returning C.
+If either operand is of C type,
+converts both operands to C and does division returning C.
If the denominator is zero, returns either C<+Inf>, C, or C<-Inf>
as the numerator is positive, zero, or negative. (This is construed
as the best default in light of the operator's possible use within
@@ -507,6 +564,11 @@
on an individual scalar division, you can always check the denominator
yourself.)
+If both operands are of integer type, you still get a C, but the
+C type is allowed to do the division lazily; internally it may
+store a C until the time a value is called for. If converted
+to C directly no division ever need be done.
+
=item *
infix:, generic division
@@ -529,7 +591,7 @@
infix:<%>, modulus
-%
+$x
'x' vs. 'xx'
Is there any reason why we can't simply define '$a x $n' as being shorthand for 'cat($a xx $n)'? In what way does the former differ from the latter, other than the use of a Whatever in place of $n? -- Jonathan "Dataweaver" Lang
Re: 'x' vs. 'xx'
On 6/2/07, Jonathan Lang <[EMAIL PROTECTED]> wrote: Is there any reason why we can't simply define '$a x $n' as being shorthand for 'cat($a xx $n)'? In what way does the former differ from the latter, other than the use of a Whatever in place of $n? -- Jonathan "Dataweaver" Lang "$a x $n" is equivalent to "join '', $a xx $n", but that isn't an apt description of its behavior. "cat($a xx *)" is an attempt to provide an infinite string since 'a' x Inf would result in memory overflow (but the cat trick works since lists are evaluated lazily).
Re: 'x' vs. 'xx'
Chas Owens wrote: Jonathan Lang wrote: > Is there any reason why we can't simply define '$a x $n' as being > shorthand for 'cat($a xx $n)'? In what way does the former differ > from the latter, other than the use of a Whatever in place of $n? "$a x $n" is equivalent to "join '', $a xx $n", but that isn't an apt description of its behavior. "cat($a xx *)" is an attempt to provide an infinite string since 'a' x Inf would result in memory overflow (but the cat trick works since lists are evaluated lazily). Then it looks to me like 'cat($a xx $n)' is more flexible than "join '', $a xx $n", and would work better as the baseline definition for '$a x $n'. Is there any reason to prefer a join-based definition to a cat-based one? AFAICT, the only thing that 'join' can do that 'cat' can't is to provide a delimiter when stitching the component strings together; in the case of 'x', this feature is (rightfully) not being used. -- Jonathan "Dataweaver" Lang
