parallel-shifty.raku

use v6.d;

class Shifty does Positional does Iterable {
    has Channel:D $.channel is required;
    has $.open is rw = True;
    method shift {
        LEAVE $.open = False if self.channel.closed;
        self.channel.receive;
    }
    method iterator {
        class :: does Iterator {
            has $.channel;
            method pull-one {
                $.channel.closed ?? IterationEnd !! $.channel.receive
            }
        }.new(:$.channel)
    }
    method Bool { $.open }
    method elems { $.open ?? ∞ !! 0 }
    method Numeric { $.open ?? NaN !! 0 }
    method is-lazy { True }
}

sub consumer(+@a) {
    .say for @a;
    # say @a.shift while @a
}

my Channel:D $c.=new;

start {
    sleep 0.1;
    $c.send(.item) for ^10;
    $c.close;
}

my @shifty := Shifty.new(:channel($c));

consumer(@shifty);