How to do something functionally with all the elements of a list in Perl 6?

Question

For example I have an Array with numbers:

> my @a = ^5
[0 1 2 3 4]

and I want to print their squares. I can use map, but it will also return a modified List (these five Trues), which I don't want:

> @a.map({ put $_**2 })
0
1
4
9
16
(True True True True True)

The only way I've found is to use hyper >>:

> @a>>.&{ put $_**2 }
0
1
4
9
16

but

• the syntax is a bit clumsy (probably I don't do it as supposed)
• what if I don't want it to work with hyper?

So what is the right way to do it?

P.S. Of course, I can use map and then put the result:

.put for @a.map: {$_**2 }

but that's not what I want.

Answer 1

Using map is fine for this purpose, since in sink context it will not produce a result list. In the REPL, the result of the map is wanted, thus why it is produced. But in a case like:

@a.map({ put $_**2 });
say "That's all, folks";

Then the result of the map is not wanted, and so no list of results will be assembled. If wishing to really spell this out, it's possible to write:

sink @a.map({ put $_**2 })

Be aware that the last statement in a routine is taken as an implicit return value. Using --> Nil will suffice to ensure a final map is in sink context instead.

sub put-squares(@a --> Nil) {
    @a.map({ put $_**2 })
}