perl -E 'our @array = (1,2,3); *1=\@array; say for @1;'
1
2
3

##</code><code>##

# $1 will be undef, so not relevant to the pattern. [0] will be a single-character character class, so matches "0".
perl -E 'our @array = (1,2,3); *1=\@array; say for @1; say "yes" if "0" =~ m/.?${1}[0]/;'
1
2
3
yes

##</code><code>##

# $1[0] is seen as interpolation, placing the value of "1" into the regexp, which matches with the "1" in our target string.
perl -E 'our @array = (1,2,3); *1=\@array; say for @1; say "yes" if "1" =~ m/.?$1[0]/;'
1
2
3
yes