I noticed that PostgreSQL and Perl 6 have the same syntax for junctions (well, at least any) 

samv=# select s from generate_series(1,20) s where s = any (select y f
+rom generate_series(18,23) y)
;
 s  
----
 18
 19
 20
(3 rows)

[download]

This year's perl:

perl -MPerl6::Junction=any -le 'for my $s (1..20) { if ($s == any(18..23) ) { print $s } }' 

$h=$ENV{HOME};my@q=split/\n\n/,`cat $h/.quotes`;$s="$h/."
."signature";$t=`cat $s`;print$t,"\n",$q[rand($#q)],"\n";

[download]

Replies are listed 'Best First'.
Re: Perl 6 Junctions and Postgres SQL
by dragonchild (Archbishop) on Dec 22, 2007 at 15:10 UTC
    In other words, PostgreSQL provides an alias for "WHERE s IN (...)" and calls it "WHERE s = ANY(...)". Forgive me for being underwhelmed.

    It's not surprising that SQL is going to look at a lot like the junction operators - both operate on sets*. A relational database is nothing more than a set theory machine. The junction operators are similar. You even have all() and one() in SQL; they're just not in the forms you're thinking of.

    *: Yes, the junction operators deal with lists, but they treat the lists as sets.

    My criteria for good software:
    1. Does it work?
    2. Can someone else come in, make a change, and be reasonably certain no bugs were introduced?
[reply]

      I share your sentiments. Still, all is not lost. I was happy to hear of the generate_series thing. I don't know how directly this can be transposed to another DB, (thinking of Oracle here), but I do know that at times it can be nice to have a select generate a huge amount of arbitary data on the fly.

      The other day I needed to blend the numbers 1..19999 into a select, and after considering a select ... union select from dual for about a microsecond, I created a table with a single column containing the numbers from 1 to 19999. Sort of ugly, but it got the job done.

      • another intruder with the mooring in the heart of the Perl

[reply]
Re: Perl 6 Junctions and Postgres SQL
by perlostitute (Initiate) on Dec 21, 2007 at 22:57 UTC

    How so?

[reply]

      Ok, piece by piece: 

      (select y from generate_series(18,23) y)
(select s from generate_series(1,20) s)

      [download]

      Is similar to, respectively: 

      (18..23)
(1..20)

      [download]

      Then this query:

      select s from (1..20) where s = any( 18..23 )

      Is similar in meaning to this: 

      for my $s (1..20) {
    if ($s == any(18..23) ) {
        print $s;
    }
}

      [download]

      Or, more close in expression to the SQL, the Perl 6:

      [1..20].grep:{ $_ == any(18..23) }.say

      Hmm, wouldn't it be useful to have a LINQ to Hyper-operator/Junction cheat-sheet... 

      $h=$ENV{HOME};my@q=split/\n\n/,`cat $h/.quotes`;$s="$h/."
."signature";$t=`cat $s`;print$t,"\n",$q[rand($#q)],"\n";

      [download]
[reply]
[d/l]
[select]
        Toying with perl 5.10: 
        perl -E 'for(1..20) { when([18..23]) { say } }'

        [download]
        :-)

        I'm slightly puzzled that I couldn't write when(18..23), though.

[reply]
[d/l]
[select]

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