misterperl has asked for the wisdom of the Perl Monks concerning the following question:

(Perl 5.16 on linux).. I often prefer postfix expressions, like  say $_ for 1..10;

As a natural extension, I'd like to use nested postfix loops. ChatGPT suggested: 

  say $_ for 1..5 for 1..10;

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which seemed a strange proposition, because how could the scalar $_ contain both $i and $j? I tried it, thinking: "I gotta SEE this!". I thought perhaps Perl was clever enough to make $_ a reference to a list, but say or print of that would only be the reference, which was even more perplexing why it was suggested.But it only throws a syntax error on the second "for".

TY

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Re: postfix "for" question?
by SankoR (Prior) on Sep 11, 2023 at 14:31 UTC

    I wouldn't expect ChatGPT to generate valid Perl; it's hard enough for human beings to do that without knowing Perl.

    do { CORE::say $_ for 1 .. 5 } for 1 .. 10;

    You could try that. I wouldn't. But you could.

    Edit: Even more convoluted: do { CORE::say $_ for 1 .. $_ } for 1 .. 10;. I guess tinkering like this helps figure out how context and loops work, if that's the goal.
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      well my REAL goal, if truth be told, as an APL-trained programmer, is to seek ways to produce a result in the fewest number of characters... Removing {} not only helps reach that goal, it makes things much more English-like..

      TY!

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        perl -E 'say for (1 .. 5) x 10'

        This solution is brought to you without the help hindrance of ChatGPT.

        🦛

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[d/l]

        How about 

        map CORE::say, 1..5 for 1..10

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        map is almost postfix and almost like a for

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Re: postfix "for" question?
by LanX (Saint) on Sep 11, 2023 at 16:40 UTC
    ChatGPT is a text generator, not a programming tool.

    This code is just 🐂💩

    Cheers Rolf
    (addicted to the 𐍀𐌴𐍂𐌻 Programming Language :)
    Wikisyntax for the Monastery

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      I think I (understand and) agree with what you mean, but not with the wording. Text generators are programming tools, too.

      GhatGPT is not sophisticated enough to be reliably used as a programming tool.
      (While it may be highly sophisticated in several other regards, but it is not in this regard…)
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        All code generators are text generators, true. But not the other way round.

        Cheers Rolf
        (addicted to the 𐍀𐌴𐍂𐌻 Programming Language :)
        Wikisyntax for the Monastery

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Re: postfix "for" question?
by karlgoethebier (Abbot) on Sep 12, 2023 at 10:59 UTC

     perl -E 'map {say 1..10} 1..5'

    «The Crux of the Biscuit is the Apostrophe»

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[d/l]

      Not quite. 

      perl -E 'map {say for 1..10} 1..5'

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[d/l]

        This was actually intentional as it looks better:

        Karl@h3002993:~$ perl -E 'map {say 1..10} 1..5'
12345678910
12345678910
12345678910
12345678910
12345678910

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        Or:

        
karl@h3002993:~$ perl -E 'map {say join " ", 1..10} 1..5'
1 2 3 4 5 6 7 8 9 10
1 2 3 4 5 6 7 8 9 10
1 2 3 4 5 6 7 8 9 10
1 2 3 4 5 6 7 8 9 10
1 2 3 4 5 6 7 8 9 10

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        Compared to:

        karl@h3002993:~$ perl -E 'map {say for 1..10} 1..5'
1
2
3
4
5
6
7
8
9
10
1
2
3
4
5
6
7
8
9
10
1
2
3
4
5
6
7
8
9
10
1
2
3
4
5
6
7
8
9
10
1
2
3
4
5
6
7
8
9
10

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        Update: Probably I meant  perl -E 'map {print for 1..10,"\n"} 1..5'

        «The Crux of the Biscuit is the Apostrophe»

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