New Toys in Perl 6: custom ops.

Rakudo is just starting to get support for adding custom operators to the grammar from user-level code. You can’t specify the precedence yet, but you can run the traditional examples:

multi sub infix:<±>(Int $a, Int $b) { return $a + $b | $a - $b }
multi sub postfix:<!>(Int $a where { $_ > 0 }) { return [*] 1..$a }

my $x = 5! ± 2;
say "hi dood" if $x > 121;
say "hello again" if $x < 119;

I was playing around today with defining operators for mathematical set operations (∩ ∪ ∖ ⊂ ⊃ ⊆ ⊇ etc.) and then decided that I wanted a fancy syntax for defining sets, so I added support to rakudo for circumfix operator definition, and i now have this running on rakudo:

say "subset" if ⦃ 1, 3, 5 ⦄ ⊆ ⦃ 1, 2, 3, 4, 5 ⦄;