(You do not want to change $n, so ++ is out of the question)

Also note that currently $n cannot be a native int when using ++, though that will be fixed.

$ perl6 -e'my Int $n = 10; say ++$n;'
11
$ perl6 -e'my int $n = 10; say ++$n;'
Cannot assign to an immutable value
  in sub prefix:<++> at src/gen/m-CORE.setting:5565
  in block <unit> at -e:1
$ perl6 -e'my int $n = 10; say [+] ^$n'
45
$ perl6 -e'my int $n = 10; say [+] ^$n,$n'
55
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