getting every possible substring in perl - perl

Question

I would like to generate every possible consecutive substring of a string, including the end of the word/beginning from the word (cyclic) letter combinations. I've found an example in Python, but the only language I know is perl (and barely, I'm a beginner). I would appreciate it a lot if someone can help me translating the code to perl or to help me find a solution in perl.
the code is the following:
aa='ABCD'
F=[]
B=[]
for j in range(1,len(aa)+1,1):
for i in range(0,len(aa),1):
A=str.split(((aa*j)[i:i+j]))
B=B+A
C=(B[0:len(aa)*len(aa)-len(aa)+1])
it gives you:
C=['A', 'B', 'C', 'D', 'AB', 'BC', 'CD', 'DA', 'ABC', 'BCD', 'CDA', 'DAB', 'ABCD']`

Answer 1

#!/usr/bin/perl
use warnings;
use strict;
use feature qw{ say };
my $string = 'ABCD';
my #substrings;
for my $length (1 .. length $string) {
for my $pos (0 .. length($string) - 1) {
push #substrings, substr $string x 2, $pos, $length;
}
}
say for #substrings;

Answer 2

If you're interested in using a pre-built solution, you could checkout the CPAN, where I found the module String::Substrings. Because you want "wrap-around" substrings and want to eliminate the "substrings" that have the same length as the actual string, you'll have to do a little manipulation:
#!/usr/bin/perl
use strict;
use warnings;
use String::Substrings;
use feature 'say';
my $string = 'ABCD';
my %substrs;
for my $len (1..length($string)-1) {
$substrs{$_}++ for substrings("$string"x2, $len);
}
say for sort keys %substrs;
Results:
A
AB
ABC
B
BC
BCD
C
CD
CDA
D
DA
DAB