Thank you, Brad and Larry, for explaining the "ff" and "fff" infix operators in Raku to me!
I have to admit that I'm still fuzzy on the particulars between "ff" and "fff", since I am not familiar with the sed function. I can certainly understand how useful these functions could be to 'pull out all PGP signatures' from a file (which was the Perl5 example given in the Oracle Linux Blog). So I can now pull out the html "head" section from the page _ https://raku.org/fun/ _ (saved locally as file "fun.txt") using the following Raku code: user@mbook:~$ raku -ne '.put if Q[<head>] ff Q[</head>]' fun.txt <head> <meta charset="utf-8"> <meta http-equiv="X-UA-Compatible" content="IE=edge"> <meta name="viewport" content="width=device-width, initial-scale=1"> <title>Raku is optimized for fun!</title> <link href="/favicon.ico" rel="shortcut icon" type="image/x-icon"> <link href="/bootstrap/css/bootstrap.min.css" rel="stylesheet"> <link href="/bootstrap/css/bootstrap-theme.min.css" rel="stylesheet"> <link href="/style.css?v=1" rel="stylesheet"> </head> user@mbook:~$ What I'm less clear on is how the code below is functioning. I first print out file named "startling.txt" with 'cat': it's supposed to stand in for a text delimited linewise by "header 1", "header 2", etc. After the 'cat' example, I show three examples with Perl(v5.26.3) and three examples with Raku(2020.06), generally comparing literal vs regex arguments. The first two Perl5 examples returns nothing; the third Perl5 example returns everything after the "star" line. For the Raku code, the 'DWIMmiest' output below is the first Raku example, which returns two lines, "star" and "start". This is what I expected/desired. But I'm not really understanding what's happening with the other 2 Raku examples (which return everything after the "star" line): user@mbook:~$ cat startling.txt s st sta star start startl startli startlin startling user@mbook:~$ perl -nE 'print if "star" .. "start" ;' startling.txt user@mbook:~$ perl -nE 'print if /"star"/ .. /"start"/ ;' startling.txt user@mbook:~$ perl -nE 'print if /star/ .. /start/ ;' startling.txt star start startl startli startlin startling user@mbook:~$ raku -ne '.put if "star" ff "start" ;' startling.txt star start user@mbook:~$ raku -ne '.put if /"star"/ ff /"start"/ ;' startling.txt star start startl startli startlin startling user@mbook:~$ raku -ne '.put if /star/ ff /start/ ;' startling.txt star start startl startli startlin startling user@mbook:~$ I'm all in favor of improving the "ff" and "fff" functions in Raku over their Perl5 counterparts, but I'm hoping to gain a better (mnemonic?) way of remembering the expected return values with literal vs regex arguments. Any assistance appreciated, Bill. On Sun, Jul 26, 2020 at 10:04 AM Larry Wall <la...@wall.org> wrote: > > On Sat, Jul 25, 2020 at 04:32:02PM -0500, Brad Gilbert wrote: > : In the above two cases ff and fff would behave identically. > : > : The difference shines when the beginning marker can look like the end > : marker. > > The way I think of it is this: You come to the end of "ff" sooner, so you > do the end test immediately after passing the start test. You come to the > end of "fff" later, so the end test is delayed to the next iteration from > the start test. (Same mnemonic for .. and ... in Perl, by the way, since > ff and fff were modeled on .. and ... (in their scalar form), but we stole > .. and ... in Raku for ranges and sequences so we needed something else.) > > I suppose if you're musical you can come up with mnemonics based on "fff" > being louder than "ff", so it echoes longer before it stops... :) > > Larry
