> I've no idea what all(@ar1) < any(@ar2) would be, I guess it would check that max(ar1) < max(ar2)?

It seems that it just expands the lists using the operator. The output from junctions is quite nice:

    > my @a = <1 2 3 4>;
    > my @b = <2 3>;
    > say all(@a) < any(@b);
    all(any(True, True), any(False, True), any(False, False), any(False, False))
    > say so all(@a) < any(@b);
    False

This looks awful to my (mathematically trained) eyes. What is the rationale behind introducing this language feature?

* Seems kinda cool

* Makes $x == 5|6 look kinda cool

* $string ~~ /<first>/ & /<second>/ & /<third>/ # matches all three regexes. huh. kinda cool

* (5|6).foo maybe we can do that in cpu-parallel (it doesn't now)? That might be kinda cool

* sub is-prime($n where $n > 2) { $n % none(2..sqrt($n)) == 0 } # Logical O(1) prime test if only you had that quantum-coprocessor? That... would be kinda cool

* ... you might notice a pattern to the motivation for this feature :)

I really couldn't tell you. I guess "it's perl, we can"?

One that I recall that I'm hoping still applies is having a syntactically and conceptually lightweight way to express semantically parallel computation logic. Given the code:

  junction1 = val1 | val2 | val3;
  junction2 = val4 & val5;
  if junction1 op junction2 { ... };

the compiler is free to fire off several threads, or set up a lower level SIMD parallel process, with short-circuiting, to compute the conditional result.

Could you explain why you think this is awful? Perl 6 has proper sets, bags and the appropriate operators for 'normal' set operations too.

  no idea what all(@ar1) < any(@ar2) would be

Subset?

I think that means something like all the individual values in the @ar1 list of values are less than at least one of the individual values in @ar2.

Yes exactly. To take the code snippet a cousin-reply mentioned one step further, swaping @a and @b:

    > my @a = <1 2 3 4>;
    [1 2 3 4]
    > my @b = <2 3>;
    [2 3]
    > say so all(@a) < any(@b);
    False
    > say so all(@b) < any(@a);
    True