The repeat operator (x) can be used with hash slices to get an easy to read set representation:

my @fruit_set = qw/apple banana orange mango/;
my @vegie_set = qw/onion tomato lettuce eggplant/;

my (%fruit, %vegetable);
@fruit{@fruit_set}     = (1) x @fruit_set;
@vegetable{@vegie_set} = (1) x @vegie_set;
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