From @titsuki

See the following result​:

$ perl6 -e 'my $proc = Proc​::Async.new("yes"); $proc.stdout.head(1).tap(&say); await $proc.start;'

y
y
y
y
y
y
y
y
...

I think tap(&say) should output just a 'y' char and completes its work.

$ perl6 --version
This is Rakudo version 2017.09-254-gde0533c4d built on MoarVM version 2017.09.1-575-gd4e230a69
implementing Perl 6.c.

From @geekosaur

On Sat, Oct 7, 2017 at 10​:21 PM, Itsuki Toyota <perl6-bugs-followup@​perl.org

wrote​:

See the following result​:

$ perl6 -e 'my $proc = Proc​::Async.new("yes");
$proc.stdout.head(1).tap(&say); await $proc.start;'

y
y
y
y
y
y
y
y
...

I think tap(&say) should output just a 'y' char and completes its work.

No guarantee it's line based, nor do pipes deliver output in lines. You
wanted a .lines in there to 'rechunk' the output; otherwise I suspect you
get blocks based on the size of am OS pipe buffer, or similar.

https://docs.perl6.org/type/Supply#method_lines

--
brandon s allbery kf8nh sine nomine associates
allbery.b@​gmail.com ballbery@​sinenomine.net
unix, openafs, kerberos, infrastructure, xmonad http://sinenomine.net

The RT System itself - Status changed from 'new' to 'open'

From @AlexDaniel

I created this doc issue​: Raku/doc#1591

On 2017-10-07 19​:33​:40, allbery.b@​gmail.com wrote​:

On Sat, Oct 7, 2017 at 10​:21 PM, Itsuki Toyota <perl6-bugs-followup@​perl.org

wrote​:

See the following result​:

$ perl6 -e 'my $proc = Proc​::Async.new("yes");
$proc.stdout.head(1).tap(&say); await $proc.start;'

y
y
y
y
y
y
y
y
...

I think tap(&say) should output just a 'y' char and completes its work.

No guarantee it's line based, nor do pipes deliver output in lines. You
wanted a .lines in there to 'rechunk' the output; otherwise I suspect you
get blocks based on the size of am OS pipe buffer, or similar.

https://docs.perl6.org/type/Supply#method_lines

From @jnthn

On Sat, 07 Oct 2017 19​:33​:40 -0700, allbery.b@​gmail.com wrote​:

On Sat, Oct 7, 2017 at 10​:21 PM, Itsuki Toyota <perl6-bugs-followup@​perl.org

wrote​:

See the following result​:

$ perl6 -e 'my $proc = Proc​::Async.new("yes");
$proc.stdout.head(1).tap(&say); await $proc.start;'

y
y
y
y
y
y
y
y
...

I think tap(&say) should output just a 'y' char and completes its work.

No guarantee it's line based, nor do pipes deliver output in lines. You
wanted a .lines in there to 'rechunk' the output; otherwise I suspect you
get blocks based on the size of am OS pipe buffer, or similar.

https://docs.perl6.org/type/Supply#method_lines

Indeed; the Supply objects returned from Proc​::Async just pass on the data that arrives, as it arrives, in the chunks that it arrives in. Often one wants all of the output, so parsing it into lines by default would just add a load of overhead to that case. The `.lines` method is the correct way for those wanting line-by-line output.

From @AlexDaniel

I'll close this in favor of the doc issue mentioned above.

I'm pretty sure this needs a corresponding [DETRAP] ticket, but that tag is not a thing *yet*. For now we only document these things. Eventually I'll get to it, but this a long-term thingie (like v6.d or v6.e or whatever).

On 2017-10-09 01​:27​:33, jnthn@​jnthn.net wrote​:

On Sat, 07 Oct 2017 19​:33​:40 -0700, allbery.b@​gmail.com wrote​:

On Sat, Oct 7, 2017 at 10​:21 PM, Itsuki Toyota <perl6-bugs-
followup@​perl.org

wrote​:

See the following result​:

$ perl6 -e 'my $proc = Proc​::Async.new("yes");
$proc.stdout.head(1).tap(&say); await $proc.start;'

y
y
y
y
y
y
y
y
...

I think tap(&say) should output just a 'y' char and completes its
work.

No guarantee it's line based, nor do pipes deliver output in lines.
You
wanted a .lines in there to 'rechunk' the output; otherwise I suspect
you
get blocks based on the size of am OS pipe buffer, or similar.

https://docs.perl6.org/type/Supply#method_lines

Indeed; the Supply objects returned from Proc​::Async just pass on the
data that arrives, as it arrives, in the chunks that it arrives in.
Often one wants all of the output, so parsing it into lines by default
would just add a load of overhead to that case. The `.lines` method is
the correct way for those wanting line-by-line output.

@AlexDaniel - Status changed from 'open' to 'rejected'