Ok, in order not to waste your time, this is my proposal, different from the
existing and consistent with the rest of C++.

1. Syntax

Having a function type like this:

 typedef int filter_int( int );

We can use it to define a lambda construct:

 transform( v1, v2, filter_int( auto i ) { return i*2; } );

Using variadic template feature, a generic function type can be created and
added to the standard library, say, std::lambda.


2. Memory management and closures

State such a function:

int accm( const vector<int>& v )
{
 int n = 0;
 for_each( v, lambda<void>( int i ) { n += i; } );
 return n;
}

The 'n' here is accessed via reference, because the lambda is passed also via
reference:

template<typename F, Container C >
F for_each( C& c, F& f ) {  ... }

If the lambda is passed via value, the closure variables are also accessed via
value.


Comments welcome. Should I provide rationale, just follow up or mail me at:
ethouris(at)gmail.com


--
//  _    ___         Michal "Sektor" Malecki <sektor(whirl)kis.p.lodz.pl>
\\ L_ |/ `|  /^\ ,()                         <ethouris(O)gmail.com>
// \_ |\  \/ \_/ /\ C++ bez cholesterolu: http://www.intercon.pl/~sektor/cbx
"Java is answer for a question that has never been stated"

---
[ comp.std.c++ is moderated.  To submit articles, try just posting with ]
[ your news-reader.  If that fails, use mailto:std-c++@ncar.ucar.edu    ]
[              --- Please see the FAQ before posting. ---               ]
[ FAQ: http://www.comeaucomputing.com/csc/faq.html                      ]