"Shannon Stewman" <stew@uchicago.edu> wrote in message news:20040304025205.GD832@uchicago.edu...

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On Wed, Mar 03, 2004 at 01:34:50PM -0800, Powell, Gary wrote:

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unsigned long n = std::accumulate( xs.begin(), xs.end(), 0UL, long (long lhs, X const &rhs) // inline fn with no

name.

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{ return lhs + rhs.count; } );

This seems to cast out the type inference present in BLL. I think that's one of the nicer concepts in the lambda library, and a real boon to programming. In my limited experience with SML/OCaml, type inference seems a better, safer, and more convenient way to program, albeit requiring a lot more compiler intelligence. As BLL shows,

though,

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this is quite possible, though perhaps limited, with existing C++.

How about:

unsigned long n = std::accumulate( xs.begin(), xs.end(), 0UL, auto(long lhs, const auto& rhs) // inline fn with no name. { return lhs + rhs.count; } );

I would prefer also eliding the argument types:

unsigned long n = std::accumulate( xs.begin(), xs.end(), 0UL, lambda(lhs, rhs) { return lhs + rhs.count; } );

Most of the time, you also do not know the type of the arguments before hand.

Joel de Guzman

There are still direct templates (even without implied ones.) The syntax would be a bit verbose though. unsigned long n = std::accumulate( xs.begin(), xs.end(), 0UL, template<class T, class S) auto (T const &lhs, S const &rhs) { return lhs + rhs.count; } );