See https://docs.perl6.org/language/quoting for more information.
Really you only need to remember that ' ' is very bare-bones, while " " has
more features.
---
Single quotes only allow \\, \qq[...] and escaping the delimiter with \
(All other backslashes are left as they are in the text.)
While double quotes also enable :s, :a, :h, :f, :c, :b modes
"\t" =:= Q :s :a :h :f :c :b [\t]
:s / :scalar --- interpolate $ vars
:a / :array --- interpolate @ vars
:h / :hash --- interpolate % vars
:f / :function --- interpolate & calls
:c / :closure --- interpolate {} closures
:b / :backslash --- enable backslash escapes (\n, \qq, \$foo, etc)
(:b / :backslash is a superset of :q / :single)
Note that 'foo' is really short for all of these:
Q :q [foo]
Q :single [foo]
q [foo]
(The two characters [ ] can be just about any non-alphanumeric characters.)
and "foo\n" is short for these
Q :qq [foo\n]
Q :double [foo\n]
Q :s :a :h :f :c :b [foo\n]
Q :scalar :array :hash :function :closure :backslash [foo\n]
q :s :a :h :f :c :b [foo\n]
q :scalar :array :hash :function :closure :backslash [foo\n]
qq [foo\n]
This can be useful for say embedding a scalar variable, while @ is litteral.
Q :scalar [[email protected]]
You can even turn off features
qq :!array [[email protected]]
There is also ｢ ｣ (and Q) which has no features. (You can't even escape the
delimiter.)
'abc\\' =:= ｢abc\｣ =:= Q [abc\]
---
P.S. Note that I added spaces for clarity, in most cases they aren't
actually needed.
Q:scalar:array:hash:function:closure:backslash[foo\n]
Also :q follows all of the rules of adverbs, except that in this case they
have to be compile-time values
qq :array(False) [[email protected]]
On Wed, Jul 31, 2019 at 7:30 PM William Michels via perl6-users <
[email protected]> wrote:
> Great explanation, Andy. Thank you! Actually it's pretty exciting that
> split now works as a method in perl6, including splitting on a regex
> as in ".split(/\:+/)" ...see first line below (REPL example):
>
> > say $_ =
> "apple:banana:carrot:dragonfruit::favabean".split(/\:+/).join("\t");
> apple banana carrot dragonfruit favabean
> > say $_ = .split("\t").join("_");
> apple_banana_carrot_dragonfruit_favabean
> > say $_ = .split("_").join(";");
> apple;banana;carrot;dragonfruit;favabean
> > say $_ = .split(";")[0,2,1,4].join("|");
> apple|carrot|banana|favabean
> > say $_.perl
> "apple|carrot|banana|favabean"
> > put $_
> apple|carrot|banana|favabean
> >
>
> Still trying to figure out why split will take single-quoted literals
> like ':' but join appears to require a double-quoted $separator as in
> "\t" or "\n" (example below). In the last line, it seems that escaped
> characters must be double-quoted, while non-escaped separators can be
> single-quoted. At least that's what I'm concluding... . --Best, Bill.
>
> > say $_ = "apple|carrot|banana|favabean"
> apple|carrot|banana|favabean
> > say .split(/\|+/).join('\n');
> apple\ncarrot\nbanana\nfavabean
> > say .split(/\|+/).join("\n");
> apple
> carrot
> banana
> favabean
> > say $_ =
> "apple:banana:carrot:dragonfruit::favabean".split(/\:+/)[0,2,1,4].join('____');
> apple____carrot____banana____favabean
>
> >
>
>
>
> On Wed, Jul 31, 2019 at 3:28 PM Andy Bach <[email protected]>
> wrote:
> >
> > > , but I had to change .split(':') either to .split(":") or
> >
> > because your -e ' .... ' quotes are the same, so bash breaks it up into
> 3 chunks
> > say .split(
> > :
> > )[0, 2, 1, 5].join("\t") for
> >
> > and perl just gets the first as the "program"
> >
> > ________________________________
> > From: William Michels via perl6-users <[email protected]>
> > Sent: Wednesday, July 31, 2019 4:28 PM
> > To: Patrick R. Michaud <[email protected]>
> > Cc: perl6-users <[email protected]>
> > Subject: Re: while(<>){...} analog?
> >
> > Hi Patrick, I used both your examples as perl6 one-liners. I'm not
> > sure why, but I had to change .split(':') either to .split(":") or
> > .split(/\:/) for both example to work. Maybe it's a command-line
> > thing? Possibly because I'm on a Mac? Also, to get the second example
> > to work I change the 'for lines' preamble to 'for lines()' then it's
> > fine (otherwise perl6 balks with an awesome error: "Function 'lines'
> > needs parens to avoid gobbling block").
> >
> > Thanks again for all your help! --Best, Bill.
> >
> > # test file: six_fruits1.txt
> > mbook:~ homedir$ cat six_fruits1.txt
> > apple:banana:carrot:dragonfruit:eggplant:favabean
> > apricot:basil:cabbage:dill:escarole:fennel
> > acai:beets:celery:daikon:endive:figs
> >
> > # First example:
> > mbook:~ homedir$ perl6 -e 'say .split(":")[0, 2, 1, 5].join("\t") for
> > lines' six_fruits1.txt
> > apple carrot banana favabean
> > apricot cabbage basil fennel
> > acai celery beets figs
> > mbook:~ homedir$ perl6 -e 'say .split(/\:/)[0, 2, 1, 5].join("\t") for
> > lines' six_fruits1.txt
> > apple carrot banana favabean
> > apricot cabbage basil fennel
> > acai celery beets figs
> >
> > # Second example: note changed 'for lines' to 'for lines()'
> > mbook:~ homedir$ perl6 -e ' for lines() { say .split(":")[0, 2, 1,
> > 5].join("\t") }' six_fruits1.txt
> > apple carrot banana favabean
> > apricot cabbage basil fennel
> > acai celery beets figs
> > mbook:~ homedir$ perl6 -e ' for lines() { say .split(/\:/)[0, 2, 1,
> > 5].join("\t") }' six_fruits1.txt
> > apple carrot banana favabean
> > apricot cabbage basil fennel
> > acai celery beets figs
> >
> >
> > On Mon, Jul 29, 2019 at 12:56 PM Patrick R. Michaud <[email protected]>
> wrote:
> > >
> > > My guesses at Perl 6 versions of the Perl 5 example:
> > >
> > > say .split(':')[0, 2, 1, 5].join("\t") for lines;
> > >
> > > -or-
> > >
> > > for lines { say .split(':')[0, 2, 1, 5].join("\t") }
> > >
> > > Pm
> > >
> > >
> > > On Mon, Jul 29, 2019 at 12:49:51PM -0700, William Michels via
> perl6-users wrote:
> > > > Hello, Just a short backgrounder to say that this question arose this
> > > > past weekend at a Perl6 Meetup (Oakland, CA). Specifically we were
> > > > looking at how to write a Perl6 version of some introductory Perl5
> > > > code in "Learning Perl", 7th Edition by Tom Phoenix, brian d foy,
> > > > Randal L. Schwartz:
> > > >
> > > > #Perl 5 code below:
> > > > while (<>) {
> > > > chomp;
> > > > print join("\t", (split /:/)[0, 2, 1, 5] ), "\n";
> > > > }
> > > >
> > > >
> https://www.oreilly.com/library/view/learning-perl-7th/9781491954317/ch01.html
> > > >
> > > > (Thanks to Joseph Brenner for organizing the Perl6 Meetup).
> > > >
> > > >
> > > >
> > > >
> > > >
> > > >
> > > > On Mon, Jul 29, 2019 at 2:09 AM Elizabeth Mattijsen <[email protected]>
> wrote:
> > > > >
> > > > > Also, you can make this conditional: show me all the comment
> lines of a source file:
> > > > >
> > > > >
> > > > > $ perl6 -e '.say if .starts-with('#') for lines' source-file
> > > > >
> > > > >
> > > > > > On 29 Jul 2019, at 10:06, Richard Hainsworth <
> [email protected]> wrote:
> > > > > >
> > > > > > Also no need for all the brackets
> > > > > >
> > > > > > .say for lines;
> > > > > >
> > > > > > This is quite idiomatic Perl 6 and not golfing
> > > > > >
> > > > > > On Mon, 29 Jul 2019, 07:13 Joseph Brenner, <[email protected]>
> wrote:
> > > > > > > Hmmm. I would expect that to be in the Perl 5 to Perl 6
> Migration Guides, but I do not see it there.
> > > > > >
> > > > > > Exactly, I was just looking there, and I ended up playing around
> with
> > > > > > the method form of lines, and didn't think to try the function
> > > > > > form of it.
> > > > > >
> > > > > > To summarize, if the goal is to write a "simple_echo" script that
> > > > > > can work with a file name or with lines on standard input:
> > > > > >
> > > > > > simple_echo lines.txt
> > > > > > cat lines.txt | simple_echo
> > > > > >
> > > > > > The perl5 version would probably be:
> > > > > >
> > > > > > #!/usr/bin/env perl
> > > > > > while(<>){
> > > > > > print;
> > > > > > }
> > > > > >
> > > > > > The perl6 version would be something like:
> > > > > >
> > > > > > #!/usr/bin/env perl6
> > > > > > use v6;
> > > > > > for lines() {
> > > > > > say $_;
> > > > > > }
> > > > > >
> > > > > >
> > > > > > The kind of thing I was playing with was:
> > > > > >
> > > > > > #!/usr/bin/env perl6
> > > > > > use v6;
> > > > > > my @lines = $*ARGFILES.IO.lines;
> > > > > > say @lines;
> > > > > >
> > > > > > That works for lines from a file, but not from standard input,
> and the
> > > > > > error message isn't tremendously helpful:
> > > > > >
> > > > > > No such method 'lines' for invocant of type 'IO::Special'
> > > > > >
> > > > > >
> > > > > >
> > > > > >
> > > > > > On 7/28/19, Bruce Gray <[email protected]> wrote:
> > > > > > >
> > > > > > >
> > > > > > >> On Jul 28, 2019, at 6:20 PM, Joseph Brenner <
> [email protected]> wrote:
> > > > > > >>
> > > > > > >> I was just wondering if there's some direct analog in perl6
> to the
> > > > > > >> perl5 construct:
> > > > > > >>
> > > > > > >> while(<>){ ... }
> > > > > > >>
> > > > > > >> If I'm planning on passing a filename on the command-line, I
> can just
> > > > > > >> get it out of $*ARGFILES easily enough, but what if I also
> wanted it
> > > > > > >> to work on lines passed in via standard input?
> > > > > > >
> > > > > > >
> > > > > > > `lines` , as a sub instead of a method, and no arguments.
> > > > > > >
> > > > > > > See: https://docs.perl6.org/routine/lines#(Cool)_routine_lines
> > > > > > > Without any arguments, sub lines operates on $*ARGFILES,
> which defaults to
> > > > > > > $*IN in the absence of any filenames.
> > > > > > >
> > > > > > > For example:
> > > > > > > perl6 -e 'say .join("\t") for lines().rotor(4);'
> path/to/file.txt
> > > > > > >
> > > > > > > Hmmm. I would expect that to be in the Perl 5 to Perl 6
> Migration Guides,
> > > > > > > but I do not see it there.
> > > > > > >
> > > > > > > —
> > > > > > > Hope this helps,
> > > > > > > Bruce Gray (Util of PerlMonks)
> > > > > > >
> > > > > > >
>
