From @skids

This should say "got Nil" in there somewhere.

$ perl6 -e 'my $c = Channel.new; my $s = $c.Supply; $s.tap​: { say "got " ~ $_ }; for 1,2,Nil,3 { say "emit " ~ $_.perl; $c.send($_) }; sleep 0.1'
emit 1
emit 2
got 1
emit Nil
got 2
emit 3
got 3

This happens because the Supply code in Channel.pm(line 114 atm) uses .poll and assumes a Nil returned from it requires checking for $!is_closed in the Channel, but, if the Channel is not closed, it does nothing rather than emitting a Nil.

From @zoffixznet

Still present in rakudo de5d9e​:

<Zoffix> m​: my $c = Channel.new; my $s = $c.Supply; $s.tap​: { say "got " ~ $_ }; for 1,2,Nil,3 { say "emit " ~ $_.perl; $c.send($_) }; sleep 0.1
<camelia> rakudo-moar de5d9e​: OUTPUT«emit 1␤emit 2␤emit Nil␤got 1␤got 2␤emit 3␤got 3␤»

From @zoffixznet

On further inspection, it would appear `Nil` is not a valid value to send through the Channel. For example, `.poll` uses it to signal that there are no values present in the Channel.

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ZZ | https://twitter.com/zoffix

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