You can't use prototypes to have the compiler check whether an argument is an integer, or an object of a certain type. Prototypes are less useful than you might think at first, and they are sometimes bloody nasty. The following doesn't do what you want:

    sub foo ($$) {....}
    my @bar = (1, 2);
    foo @bar;
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&foo isn't called with two arguments - even while @bar has two elements. Remove the prototype, and it will work as expected.

Abigail