Select Code to Download

use Algorithm::Loops qw( NextPermute );

...
do {
   print(join(', ', @list), "\n");
} while (NextPermute(@list));

There are 24 permutations of abcd, 4 taken at a time:
   abcd, abdc, acbd, acdb, adbc, adcb,
...
There are  3 combinations of abcd, 3 taken at a time:
   abc, abd, acd, bcd