Unfortunately
perl5 doesn't natively support function signatures, as we'll be getting
in perl6. Although there are likely to be some modules on
CPAN to do the job such as
Attribute::Signature. As it stands the closest thing perl has to function signatures, is
the prototype, but it's very far removed from the general interpretation of function signatures, and isn't looked upon too kindly as Tom Christiansen thoroughly illustrated in
Far More Than Everything You've Ever Wanted to Know about
Prototypes in Perl.
HTH
_________
broquaint