People would be a bit surprised to find $hash{key} returning a list. I like the fact that not even tied hashes can break this expectation. I don't think you should use $hash{key} as an all-purpose replacement for funct("key"). If you are going to provide your functionality via a "hash-like" interface, then I think you should make it act like a hash; which means that it can only take a single string as input and can only return a single value.

Next you'll be wanting to tie scalars such that $x returns a list!!

If you want to return multiple values, then you'll have to return a reference to an array.

What I did with this was that I allowed the user to specify whether they wanted a list (er, ref to array) for each hash:

tied(%hash)->WantList("always");
tied(%hash)->WantList("never");
tied(%hash)->WantList("forMultiples");
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(that isn't really a suggested interface, just a quick hack at a way to describe what I'm talking about). So each user could decide whether they wanted to write code like:

$first= $hash{key}[0];
# or
$first= $hash{key};
# or
$values= $hash{key};
$first= ref($values) ? $values->[0] : $values;
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        - tye (but my friends call me "Tye")