pushing and poping strings can be done with substr:

my( $first_char, $rest)= (substr( $string, 0, 1), substr( $string, 1))
+; 
my( $last_char, $rest)= (substr( $string, -1), substr( $string, 0, -1)
+);
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or if you really want to use push and pop:

my @char= split //, $string;
my $first_char= shift @char;
my $rest= join "", @char;
my @char= split //, $string;
my $last_char= pop @char;
my $rest= join "", @char;
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Note that using thi is slower than using substr.