Author: larry
Date: Wed Dec 5 20:50:15 2007
New Revision: 14471
Modified:
doc/trunk/design/syn/S02.pod
Log:
Some clarifications requested by brian d foy++
Modified: doc/trunk/design/syn/S02.pod
==============================================================================
--- doc/trunk/design/syn/S02.pod (original)
+++ doc/trunk/design/syn/S02.pod Wed Dec 5 20:50:15 2007
@@ -12,9 +12,9 @@
Maintainer: Larry Wall <[EMAIL PROTECTED]>
Date: 10 Aug 2004
- Last Modified: 3 Dec 2007
+ Last Modified: 5 Dec 2007
Number: 2
- Version: 120
+ Version: 121
This document summarizes Apocalypse 2, which covers small-scale
lexical items and typological issues. (These Synopses also contain
@@ -2136,9 +2136,42 @@
a => $$a :$$a
a => @$$a :@$$a (etc.)
a => %foo<a> %foo<a>:p
+ '' => $x :($x)
+ '' => <x> :<x>
+ '' => ($x,$y) :($x,$y)
+ '' => [$x,$y] :[$x,$y]
+ '' => {$x => $y} :{$x => $y}
+
+The fatarrow construct may be used only where a term is expected
+because it's considered an expression in its own right, since the
+fatarrow is parsed as a normal infix operator (even when autoquoting an
+identifier on its left). The adverbial forms are considered special
+tokens and are recognized in various positions in addition to term
+position. In particular, when used where an infix would be expected
+they modify the previous operator, ignoring the intervening term or
+parenthesized argument. The form is also used to rename parameter
+declarations and to modify the meaning of various quoting forms.
+When appended to an identifier, the adverbial syntax is used to
+generate variants of that identifier; this syntax is used for
+naming operators such as C<< infix:<+> >> and multiply dispatched
+grammatical rules such as statement_control:if. When so used the
+adverb is considered part of the name, so C<< infix:<+> >> and C<<
+infix:<-> >> are two different operators. Likewise C<< prefix:<+>
+>> is different from C<< infix:<+> >>.
+
+Either fatarrow or adverbial pair notation may be used to pass named arguments
as
+terms to a function or method. After a call with parenthesized arguments,
+only adverbial syntax may be used to pass additional arguments. This is
typically
+used to pass an extra block:
+
+ find($directory) :{ when not /^\./ }
+
+This actually falls out from the preceding rules because the adverbial block
is in
+operator position, so it modifies the "find operator".
Note that as usual the C<{...}> form can indicate either a closure or a hash
-depending on the contents. It does I<not> indicate a subscript.
+depending on the contents. It does I<not> indicate a subscript despite being
+parsed as one.
Note also that the C<< <a b> >> form is not a subscript and is therefore
equivalent not to C<.{'a','b'}> but rather to C<('a','b')>. Bare C<< <a> >>
