Use a hash slice:

    my @array = qw/foo bar baz quux/;

    my %hash;
    @hash{@array} = (1) x @array;
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If you don't care about the keys having values, but just want them to exist, you can just do:

    @hash{@array} = ();
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But now you need to test for existence in the hash by using exists:

    print "foo is there" if exists $hash{foo};
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