We have great support for input ranges and thus for the pull-based model of programming, but the standard library offers almost nothing for the push-based model :(  It utterly lacks tools for composing output ranges.

What I'd like to see working is this:

import std.stdio, std.algorithm, std.range;

void main() {
    auto printer = fork!(n => n % 2)(sink!(n => writeln("odd: ", n)),
                                                  sink!(n => writeln("even:
", n)))
        .filter!(n => n != 16)
        .map!(n => n * n);

    copy(iota(10), printer);
}

http://dpaste.dzfl.pl/612a8ad6

12-Oct-2013 22:00, Artem Tarasov пишет:
> We have great support for input ranges and thus for the pull-based model
> of programming, but the standard library offers almost nothing for the
> push-based model :(  It utterly lacks tools for composing output ranges.
>
> What I'd like to see working is this:
>
> import std.stdio, std.algorithm, std.range;
>
> void main() {
>      auto printer = fork!(n => n % 2)(sink!(n => writeln("odd: ", n)),
>                                                    sink!(n =>
> writeln("even: ", n)))
>          .filter!(n => n != 16)
>          .map!(n => n * n);
>
>      copy(iota(10), printer);
> }
>
> http://dpaste.dzfl.pl/612a8ad6

Exactly, I even recall coming up with the same ideas on this NG. Except that I find that non-predicative fork is interesting too - just forward the same stuff to N sinks. For example, calculate a hash of a message as it's being sent to the network.

Moreover a lot of algorithms can come with *To/*Into suffix and forward stuff into an output range. IIRC I was behind that idea some time ago but got distracted with time, some things made it through though:

http://dlang.org/phobos/std_array.html#.replaceInto
(+ new API for std.regex has similar constructs with *Into suffix)

IMO you are more then welcome to champion additions in this direction.

-- 
Dmitry Olshansky