Author: larry
Date: Sat Mar 15 18:09:39 2008
New Revision: 14520
Modified:
doc/trunk/design/syn/S02.pod
Log:
Suboptimalities noted by John M. Dlugosz++
Modified: doc/trunk/design/syn/S02.pod
==============================================================================
--- doc/trunk/design/syn/S02.pod (original)
+++ doc/trunk/design/syn/S02.pod Sat Mar 15 18:09:39 2008
@@ -12,9 +12,9 @@
Maintainer: Larry Wall <[EMAIL PROTECTED]>
Date: 10 Aug 2004
- Last Modified: 15 Feb 2008
+ Last Modified: 15 Mar 2008
Number: 2
- Version: 129
+ Version: 130
This document summarizes Apocalypse 2, which covers small-scale
lexical items and typological issues. (These Synopses also contain
@@ -1367,9 +1367,10 @@
If you need to force inner context to scalar, we now have convenient
single-character context specifiers such as + for numbers and ~ for strings:
+ $x = g(); # scalar context and g()
@x[f()] = g(); # list context for f() and g()
@x[f()] = +g(); # list context for f(), scalar context for g()
- @x[+f()] = g(); # scalar context for f() and g()
+ @x[+f()] = g(); # scalar context for f(), list context for g()
# -- see S03 for "SIMPLE" lvalues
@x[f()] = @y[g()]; # list context for f() and g()
@@ -1377,6 +1378,18 @@
@x[+f()] = @y[g()]; # scalar context for f(), list context for g()
@x[f()] = @y[+g()]; # list context for f(), scalar context for g()
+Sigils used as list prefix operators may also be used to force context:
+
+ @x = $ g(); # scalar context for g()
+ $x = @ g(); # list context for g()
+ $x = % g(); # list context for g() (and coercion to hash)
+
+These may also be used in functional form:
+
+ @x = $(g()); # scalar context for g()
+ $x = @(g()); # list context for g()
+ $x = %(g()); # list context for g() (and coercion to hash)
+
=item *
There is a need to distinguish list assignment from list binding.
@@ -1432,18 +1445,21 @@
A signature object (C<Signature>) may be created with colon-prefixed parens:
- my ::MySig ::= :(Int, Num, Complex, Status :mice)
+ my ::MySig ::= :(Int, Num, Complex, Status)
Expressions inside the signature are parsed as parameter declarations
rather than ordinary expressions. See S06 for more details on the syntax
for parameters.
-Signature objects bound to C<::t> variables may be used within another
-signature to apply additional type constraints. When applied to a
-C<Capture> argument of form C<\$x>, the signature allows you to specify
-the types of parameters that would otherwise be untyped:
+Signature objects bound to type variables (as in the example above) may
+be used within other signatures to apply additional type constraints.
+When applied to a C<Capture> argument, the signature allows you to
+take the types of the capture's arguments from C<MySig>, but declare
+the (untyped) variable names yourself via an addition signature
+in parentheses:
- :(Num Dog|Cat $numdog, MySig \$a ($i,$j,$k,$mousestatus))
+ sub foo (Num Dog|Cat $numdog, MySig $a ($i,$j,$k,$mousestatus)) {...}
+ foo($mynumdog, \(1, 2.7182818, 1.0i, statmouse());
=item *
