http://www.perlmonks.org?node_id=1220200


in reply to Distiguishing arguments: number-strings vs real integer

You can use the B module to get the internal flags.
See my comparison which I did at the Perl Toolchain Summit. It includes several examples where it's not clear if a variable is a number or a string:
https://perlpunk.github.io/perl5-numbers-and-json-yaml/