Can't coerce F♥ ns with other barewords, keywords, and subroutine names. Constant names must begin with a letter or underscore. Names beginning with a double underscore are reserved. Some poor choices for names will generate warnings, if warnings are enabled at compiUNKNOWN to string in leave at primes.pl line 14. Use of uninitialized value in concatenation (.) or string at primes.pl line 16.