In practice, though, if you're going to reuse a series in your Perl 6 program, you'll want to memoize the series by binding the series to an array, like this:

my @fib := (0,1, *+* ... *);
say @fib[8];
say @fib[9]; # doesn't recalculate fib(8)
[download]

Both lists and arrays can be lazily infinite in Perl 6; the only real difference is whether the values are kept in an indexable form as they are generated. Note also that the memoization naturally uses an array rather than a hash in this case, which saves memory over those memoization techniques that must assume a hash for generality.