Author: audreyt
Date: Tue Sep 12 19:35:59 2006
New Revision: 11974
Modified:
doc/trunk/design/syn/S03.pod
Log:
* S03: Typographical and stylistic cleanups.
Also, clarify that identity values of reduce hyperoperators
is more logically defined by the way of a multi variant of zero
arity, rather than specifying it inside the proto itself.
Modified: doc/trunk/design/syn/S03.pod
==============================================================================
--- doc/trunk/design/syn/S03.pod (original)
+++ doc/trunk/design/syn/S03.pod Tue Sep 12 19:35:59 2006
@@ -12,9 +12,9 @@
Maintainer: Larry Wall <[EMAIL PROTECTED]>
Date: 8 Mar 2004
- Last Modified: 12 Sep 2006
+ Last Modified: 13 Sep 2006
Number: 3
- Version: 60
+ Version: 61
=head1 Changes to Perl 5 operators
@@ -50,7 +50,7 @@
a boolean (C<Bool>) context, and the C<[,]> list operator imposes
a function-arguments (C<Capture>) context on its arguments.
Unary sigils impose the container context implied by their sigil.
-As with Perl 5, however, C<$$foo[bar]> parses as C<$($foo)[bar]>,
+As with Perl 5, however, C<$$foo[bar]> parses as C<( $($foo) )[bar]>,
so you need C<$($foo[bar])> to mean the other way.
=item * Bitwise operators get a data type prefix: C<+>, C<~>, or C<?>.
@@ -543,7 +543,7 @@
$_ $x Type of Match Implied Matching Code
====== ===== ===================== =============
- Any Code:($) scalar sub truth match if $x($_)
+ Any Code:($) scalar sub truth match if $x($_)
Hash Hash hash keys identical match if $_.keys.sort »eq«
$x.keys.sort
Hash any(Hash) hash key intersection match if $_{any(Hash.keys)}
Hash Array hash value slice truth match if $_{any(@$x)}
@@ -602,7 +602,7 @@
you can't write:
given $boolean {
- when True {...}
+ when True {...}
when False {...}
}
@@ -610,7 +610,7 @@
given $boolean {
when .true {...}
- when .not {...}
+ when .not {...}
}
Better, just use an C<if> statement.
@@ -648,7 +648,7 @@
metaoperations--their semantics are supposed to be self-evident by
the transformation of the base operator.
-Note: spaces are never allowed between any metaoperator and the
+Note: Spaces are never allowed between any metaoperator and the
operator it's modifying, because all operators including modified
ones have to be recognized by the Longest-Token Rule, which disallows
spaces within a token.
@@ -672,7 +672,7 @@
of any assignment operators is forced to be the same as that of
ordinary assignment.
-=head2 Negated relational operators.
+=head2 Negated relational operators
Any infix relational operator may be transformed into its negative
by prefixing with C<!>. A couple of these have traditional shortcuts:
@@ -720,7 +720,7 @@
In fact, this is the I<only> form that will work for an unordered type
such as a C<Bag>:
- Bag(3,8,2,9,3,8) >>-<< 1; # Bag(2,7,1,8,2,7) ~~ Bag(1,2,2,7,7,8)
+ Bag(3,8,2,9,3,8) >>-<< 1; # Bag(2,7,1,8,2,7) === Bag(1,2,2,7,7,8)
When using a unary operator, only put the "hyper" on the side of the
single operand:
@@ -870,11 +870,15 @@
multi prefix:<[foo]> (Int $x) { 42 }
multi prefix:<[foo]> (Str $x) { fail "Can't foo a single Str" }
-However, the zero argument case must of necessity be handled by the
-proto version, since there is no type information to dispatch on.
-Operators that wish to specify an identity value should do so by
-specifying the proto listop. Among the builtin operators, C<[+]()>
-returns 0 and C<[*]()> returns 1, for instance.
+However, the zero argument case cannot be defined this way, since there
+is no type information to dispatch on. Operators that wish to specify an
+identity value should do so by specifying a multi variant that takes zero
+arguments:
+
+ multi prefix:<[foo]> () { 0 }
+
+Among the builtin operators, C<[+]()> returns 0 and C<[*]()> returns 1,
+for instance.
By default, if there is one argument, the built-in reduce operators
return that one argument. However, this default doesn't make sense
