we fixed the precedence of concatenation with respect to + (at your suggestion)

Thanks! And you're welcome. ;)

I like your first example. It is nice to have a "concat this list" option so compactly.

One of the things that I really learned to like about join '', ... is how low the precedence of comma is, so I don't have to put parens around even 'the ternary'. I agree that ?? :: should bind looser than concatenation but that also means I probably won't be doing direct concatenation of long lists of expressions. (Which is not a problem since there are better options.)

And the rest of the options are lovely.

Well, we fixed the indent part at least, though you're still on your own with trailing whitespace.

I'll have to review the lastest proposal on handling of indenting as I wasn't sold on some of the previous versions. But why don't you ignore trailing whitespace after the delimiter? I've decided that it is almost always better to do s/\s+$// over chomp because trailing whitespace is invisible and really deserves to be ignored. Tell me which line has the extra leading space and which one has the extra trailing space:

    LINE
    LINE 
     LINE
    LINE
    LINE
[download]

Sure, you can do it, if you know to look specifically for it, but it just sucks to have things that break due to such. At the very least, Perl 6 should shout "I noticed you had trailing whitespace after what would have otherwise ended your here-doc, but I didn't ignore it and that is probably why I couldn't find the end of your string". (:

Is there some value to allowing trailing whitespace to make the delimiter not the delimiter? The only value I come up with is a way to include something that looks like the delimiter in the output. I'd much prefer that be done in a much more visible way. Using such a subtle trick deserves a comment pointing out what is going on. But it is worse because (having worked even in a small company where my editor actually shows me trailing whitespace) I know that lots of editing situations don't give trailing whitespace much respect. Lots of things strip it or add it with little justification.

Surely, several of the above interpolation techniques would be better methods for including a line equal to the delimiter in the here-doc:

my $string= <<END;
You end your here-doc with a line like:
{''}END
but be sure to prevent any trailing whitespace
from sneaking in!
END
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What purpose am I missing?