### Flavio Poletti

Irreducible Perler.

# Equality is reflexive... isn't it?

I read about Perl6::Junction in an article on blogs.perl.org and I was tickled. I quickly went on CPAN to see what the module was about beyond the post above, and saw two enthusiastic reviews by two bigs (at least this is what I consider both of them).

I have to say that I was a bit disappointed in seeing that they both talked about very clear documentation, while it seemed a bit too minimal for my taste. I do agree that the test suite is complete, anyway, and it’s a useful source for examples too! The tests are indeed quite extensive, and there are also tests for something that made me curious, i.e.: “will it be possible to use junctions on both sides?”. The answer turns out to be positive, and there are tests for those cases (see the t/join.t test file for details).

One funny thing in the module is that the following both apply:

my $is_true = (all(3, 4) == any(3, 4)); my$is_NOT_true = (any(3, 4) == all(3, 4));

It actually makes sense: the first says “do all elements in the {3, 4} set have something equal to them in the {3, 4} set?”. Course they do, because 3 in the first set has 3 in the second, and 4 in the first set has 4 in the second. The second says “is any element in the {3, 4} equal to all the elements in {3, 4}?”. Course there isn’t, because 3 from the first set is equal to 3 in the second set, but fails to be equal to 4.

Hence, the (numeric) equality operator does not maintain the reflexive property here, and it seems just… weird, even though it makes perfectly sense.