As shown in the Algorithm::Permute synopsis, if you want r elements out of the n objects in each permutation,

# but also you can create r of n objects permutation generator, where 
+r <= n
my $p = Algorithm::Permute->new([1..4], 3);
[download]

A practical example is shown here, where there are n=4 objects and I take groups of r=2:

C:\usr\local\share>perl -MAlgorithm::Permute -e "my $p=Algorithm::Perm
+ute::->new([1..4],2); while(my @res=$p->next){print qq(@res\n)}"
2 1
1 2
3 2
2 3
3 1
1 3
4 2
2 4
4 3
3 4
4 1
1 4
[download]

Your example would be ...->new([1..8],5) to get permutations of length 5 from the 8 objects given. Or

C:\usr\local\share>perl -MAlgorithm::Permute -e "my $p=Algorithm::Perm
+ute::->new([1..8],5); while(my @res=$p->next){print qq(@res\n)}"
5 4 3 2 1
4 5 3 2 1
4 3 5 2 1
4 3 2 5 1
4 3 2 1 5
5 3 4 2 1
3 5 4 2 1
3 4 5 2 1
3 4 2 5 1
3 4 2 1 5
...
8 1 2 3 4
1 8 2 3 4
1 2 8 3 4
1 2 3 8 4
1 2 3 4 8
[download]