Well, its not entirely clear from your description what you're asking, but assuming that Tie::RegexpHash is something that allows regexes to be used as keys, then you'll need

my %hash;
tie %hash, 'Tie::RegexHash';
@hash{@array} = ();
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Note that the my declaration can't be included with the hash access, the hash needs to be tied first, and it's @hash{..} not %hash{...} for slicing.