If your requirement is the intersection of two sets of strings, try hash-slices:

  DB<100> @a="a".."f"
 
  DB<101> @b="d".."h"
 
  DB<102> @hash{@a}=@a;
 
  DB<103> print @hash{@b}
def
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If not, well it's an FAQ, for instance see Re: How do I compare two arrays? or do your own supersearch or site search with google.